Power supply system

ABSTRACT

A power supply system having a plurality of power systems is provided with a power output section in each of the power systems, an electrical load in each of the power systems, operating from power supplied by the power output section, main paths that connect the power output sections of adjacent ones of the power systems, an inter-system switch that establishes a conducting condition between the adjacent power systems by being turned on and establishes a disconnected condition between the adjacent power systems by being turned off, and an intra-system switch in each of the power systems, which is disposed on the main path between the power output section and the inter-system switch, and which establishes a conducting condition between the power output section and the electrical load by being turned on and establishes a disconnected condition between the power output section and the electrical load by being turned off.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. bypass application of InternationalApplication No. PCT/JP2018/031324 filed Aug. 24, 2018 which designatedthe U.S. and claims priority to Japanese Patent Applications No.2017-183010, filed on Sep. 22, 2017, and No. 2018-144219, filed on Jul.31, 2018, the contents of both of which are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a power supply system.

BACKGROUND

A power supply system having a plurality of power systems is known inthe prior art, as shown in JP 2017-141012 B. The power supply systemincludes power supplies such as batteries, etc., and electrical loads.The power supplies and the electrical loads are provided respectivelycorresponding to the plurality of power systems. The electrical loadsoperate from power supplied by the power supplies.

SUMMARY

In a power supply system according to a first aspect, the power supplysystem has a plurality of power systems, each of the power systems isprovided with a power output section that outputs electric power, and anelectrical load which operates from power supplied by the power outputsection, with the power system also having main paths that connect thepower output sections of adjacent ones of the power systems and aninter-system switch that establishes a conducting condition between theadjacent power systems by being turned on and establishes a disconnectedcondition between the adjacent power systems by being turned off, andwith each of the power systems being provided with an intra-systemswitch disposed on the main path between the power output section andthe inter-system switch, which establishes a conducting conditionbetween the power output section and the electrical load by being turnedon, and establishes a disconnected condition between the power outputsection and the electrical load by being turned off.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present disclosure will bemade clearer by the following detailed description, given referring tothe appended drawings. In the accompanying drawings:

FIG. 1 is an overall configuration diagram of an in-vehicle power supplysystem according to a first embodiment;

FIG. 2 is a diagram showing a specific configuration of a redundantload;

FIG. 3 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 4 is a time chart showing an example of an operating procedure thatis executed when an abnormality occurs;

FIG. 5 is a time chart showing an example of an operating procedure thatis executed when an abnormality occurs;

FIG. 6 is an overall configuration diagram of an in-vehicle power supplysystem according to a second embodiment;

FIG. 7 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 8 is an overall configuration diagram of an in-vehicle power supplysystem according to a third embodiment;

FIG. 9 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 10 is a flowchart showing an operating procedure that is executedwith a modification example 2 of the third embodiment when anabnormality occurs;

FIG. 11 is an overall configuration diagram of an in-vehicle powersupply system according to a fourth embodiment;

FIG. 12 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 13 is a flowchart showing a switch operation processing procedure;

FIG. 14 is an overall configuration diagram of an in-vehicle powersupply system according to a modification example of the fourthembodiment;

FIG. 15 is an overall configuration diagram of an in-vehicle powersupply system according to a fifth embodiment;

FIG. 16 is an overall configuration diagram of an in-vehicle powersupply system according to a sixth embodiment;

FIG. 17 is an overall configuration diagram of an in-vehicle powersupply system according to a seventh embodiment;

FIG. 18 is a diagram showing a condition in which a second system isdisconnected;

FIG. 19 is an overall configuration diagram of an in-vehicle powersupply system according to Modification Example 2 of the seventhembodiment;

FIG. 20 is an overall configuration diagram of an in-vehicle powersupply system according to an eighth embodiment;

FIG. 21 is an overall configuration diagram of an in-vehicle powersupply system according to a ninth embodiment,

FIG. 22 is an overall configuration diagram of an in-vehicle powersupply system according to a tenth embodiment;

FIG. 23 is an overall configuration diagram of an in-vehicle powersupply system according to a modification example of the tenthembodiment,

FIG. 24 is an overall configuration diagram of an in-vehicle powersupply system according to an eleventh embodiment;

FIG. 25 is an overall configuration diagram of an in-vehicle powersupply system according to a modification example of the eleventhembodiment;

FIG. 26 is an overall configuration diagram of an in-vehicle powersupply system according to a twelfth embodiment;

FIG. 27 is an overall configuration diagram of an in-vehicle powersupply system according to a thirteenth embodiment;

FIG. 28 is an overall configuration diagram of an in-vehicle powersupply system according to a modification example of the thirteenthembodiment;

FIG. 29 is an overall configuration diagram of an in-vehicle powersupply system according to a fourteenth embodiment;

FIG. 30 is an overall configuration diagram of an in-vehicle powersupply system according to a fifteenth embodiment;

FIG. 31 is an overall configuration diagram of an in-vehicle powersupply system according to a sixteenth embodiment;

FIG. 32 is an overall configuration diagram of an in-vehicle powersupply system according to a seventeenth embodiment;

FIG. 33 is an overall configuration diagram of an in-vehicle powersupply system according to an eighteenth embodiment;

FIG. 34 is an overall configuration diagram of an in-vehicle powersupply system according to a nineteenth embodiment;

FIG. 35 is an overall configuration diagram of an in-vehicle powersupply system according to a twentieth embodiment;

FIG. 36 is a diagram illustrating a function for detecting switchcurrent;

FIG. 37 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 38 is a diagram illustrating an example of a ground faultoccurrence location;

FIG. 39 is a diagram showing the relationship between the location ofoccurrence of a ground fault, the flow directions and magnitudes of thecurrents that flow through the switches, and the switch that isspecified as the target of a turn-off operation;

FIG. 40 is an overall configuration diagram of an in-vehicle powersupply system according to a twenty-first embodiment;

FIG. 41 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 42 is a diagram illustrating an example of a ground faultoccurrence location;

FIG. 43 is a diagram showing the relationship between the location ofoccurrence of a ground fault, the flow directions and magnitudes of thecurrents that flow through the switches, and the switch that isspecified as the target of a turn-off operation;

FIG. 44 is an overall configuration diagram of an in-vehicle powersupply system according to a twenty-second embodiment;

FIG. 45 is a flowchart showing an operating procedure that is executedwhen an abnormality occurs;

FIG. 46 is a diagram illustrating an example of a ground faultoccurrence location according to a twenty-third embodiment;

FIG. 47 is a diagram showing a relationship between the location ofoccurrence of a ground fault, the flow directions and magnitudes of thecurrents that flow through the switches, and the switch that isspecified as the target of a turn-off operation;

FIG. 48 is an overall configuration diagram of an in-vehicle powersupply system according to a twenty-fourth embodiment;

FIG. 49 is a diagram showing the relationship between the location ofoccurrence of a ground fault, the flow directions and magnitudes of thecurrents that flow through the switches, and the switch that isspecified as the target of a turn-off operation;

FIG. 50 is an overall configuration diagram of an in-vehicle powersupply system according to a twenty-fifth embodiment;

FIG. 51 is an overall configuration diagram of an in-vehicle powersupply system according to a modification example of the twenty-fifthembodiment;

FIG. 52 is an overall configuration diagram of an in-vehicle powersupply system according to another embodiment; and

FIG. 53 is an overall configuration diagram of an in-vehicle powersupply system according to another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An abnormality may occur in some of the plurality of power systems. Evenin such a case there is a requirement for enabling, as far as possible,continued use of a power supply or electrical load which is aconstituent of an abnormally operating power system and which is capableof continuing to be used, in order to suppress a decrease in thereliability of the power supply system.

The main objective of the present disclosure is to provide a powersupply system that can suppress a decrease in reliability even when anabnormality has occurred in some of a plurality of power systems.

In a power supply system according to a first aspect, the power supplysystem has a plurality of power systems, each of which is provided witha power output section that outputs electric power, and an electricalload which operates from power supplied by the power output section,with the power system also having main paths that connect the poweroutput sections of adjacent ones of the power systems and aninter-system switch that establishes a conducting condition between theadjacent power systems by being turned on and establishes a disconnectedcondition between the adjacent power systems by being turned off, andwith each of the power systems being provided with an intra-systemswitch disposed on the main path between the power output section andthe inter-system switch, which establishes a conducting conditionbetween the power output section and the electrical load by being turnedon, and establishes a disconnected condition between the power outputsection and the electrical load by being turned off.

The present disclosure includes inter-system switches and intra-systemswitches. For example, when an abnormality occurs within part of thepower systems, the abnormally operating power system can be disconnectedfrom the other power systems by means of the inter-system switches. Whenan abnormality occurs within a power system, the power output sectionand the electrical load of the power system can be disconnected from oneanother by means of an intra-system switch of the power system.According to the present disclosure, even when an abnormality occurs ina part of the plurality of power systems, at least one of the poweroutput section and the electrical load constituting a power system inwhich an abnormality has occurred can continue to be used as far aspossible, by operating the inter-system switches and intra-systemswitches. A decrease in reliability of the power supply system canthereby be suppressed.

First Embodiment

A first embodiment embodying a power supply system according to thepresent disclosure will be described in the following, referring to thedrawings. The power supply system of the present embodiment is forinstallation in a vehicle that is equipped with an engine as the mainin-vehicle machine, or in an electric vehicle equipped with a drivemotor.

As shown in FIG. 1, the power supply system includes a first system ES1and a second system ES2, as power systems. The first system ES1 includesa first power output section 11, a normal load 21 and a first redundantload 31. The second system ES2 includes a second power output section 12and a second redundant load 32. With this embodiment, each of theelectric power output sections 11 and 12 is an electrical storagedevice, specifically a storage battery such as a lead-acid storagebattery or a lithium ion storage battery, for example. The normal load21 includes, for example, at least one of a power window, an electricfan of a radiator that cools the engine coolant, a stop lamp, aninterior light, a USB power socket, and a motor that drives a mirrorwhich is disposed outside the passenger compartment.

The power supply system includes a first path ML1 and a second path ML2as main paths. The paths ML1, ML2 connect the first power output section11 of the first system ES1 and the second power output section 12 of thesecond system ES2, which is adjacent to the first system ES1. In FIG. 1,the paths ML1 and ML2 connecting the first power output section 11 tothe second power output section 12 are indicated by bold lines. In FIG.2 and subsequent figures, for convenience, members corresponding to amain path are not indicated by bold lines.

The power supply system includes an inter-system switch 100. The firstsystem ES1 includes a first intra-system switch 201, a first Aindividual switch 301A, and a first B individual switch 301B. The secondsystem ES2 includes a second intra-system switch 202 and a secondindividual switch 302. Each of the switches 201, 202, 301A, 301B, 302 isconstituted by a semiconductor switch such as a relay or MOS FET, forexample. With this embodiment, turning on any of the switches 201, 202,301A, 301B or 302 allows current to flow between the first and secondterminals of the switch. On the other hand, turning off any of theswitches 201, 202, 301A, 301B or 302 blocks current from flowing fromthe first terminal to the second terminal of the switch, and fromflowing from the second terminal to the first terminal of the switch.

The first path ML1 is connected to the second path ML2 via theinter-system switch 100. That is, the inter-system switch 100 isprovided in the main paths constituted by the paths ML1 and ML2. A firstintra-system switch 201 is provided in the first path ML1. In the firstpath ML1, the positive electrode of the first power output section 11 isconnected to the first intra-system switch 201 on the side opposite theinter-system switch 100. The negative electrode of the first poweroutput section 11 is connected to a ground point. The ground contactportion is, for example, a vehicle body. The positive electrode of thenormal load 21 is connected via the first A individual switch 301B tothe first path ML1 between the inter-system switch 100 and the firstintra-system switch 201. The negative electrode of the normal load 21 isconnected to a ground point. The positive electrode of the firstredundant load 31 is connected via the first B individual switch 301A tothe first path ML1 between the inter-system switch 100 and the firstintra-system switch 201. The negative electrode of the first redundantload 31 is connected to a ground point.

With the present embodiment, an electric power steering device isconstituted by the first redundant load 31 and the second redundant load32. This apparatus will be described referring to FIG. 2.

The first redundant load 31 includes a first drive circuit 31 a and afirst motor 31 b. With the present embodiment, the first drive circuit31 a is a three-phase inverter that converts DC power supplied from thefirst power output section 11 into AC power, converts DC power suppliedfrom the second power output section 12, transferred via theinter-system switch 100, into AC power, and outputs the converted power.The AC power that is outputted from the first drive circuit 31 a issupplied to the first motor 31 b. The first motor 31 b is a three-phasemotor and is driven by the supply of AC power to generate torque. Thefirst motor 31 b is, for example, a permanent magnet synchronous motor.

The second redundant load 32 includes a second drive circuit 32 a and asecond motor 32 b. With the present embodiment, the configuration of thesecond redundant load 32 is identical to that of the first redundantload 31. Hence, detailed description of the second redundant load 32 isomitted.

An output shaft (not shown) is connected to the respective rotors of thefirst motor 31 b and the second motor 32 b, and a steering wheel ST isconnected to these output shafts via a reduction gear or the like. Thefirst redundant load 31 and the second redundant load 32 cooperativelygenerate an assist torque that provides assistance to the vehicle driverin performing steering, while the first drive circuit 31 a and thesecond drive circuit 32 a exchange information with one other. Forconvenience of description, FIG. 2 shows a configuration in which twomotors are separately installed. However, the present invention is notlimited to this, and a configuration may be employed in which two setsof three-phase windings are wound in a single motor, with the sets ofwindings being energized from respective drive circuits.

It should be noted that it would be equally possible for the redundantloads 31 and 32 to be, for example, an electric brake device thatapplies a braking force to the wheels, a camera for monitoring thesituation in the surroundings of the vehicle, a laser radar such asLIDAR (Laser Imaging Detection and Ranging) apparatus, a millimeter-waveradar apparatus or a by-wire system. Furthermore, in the example of theelectric power steering, the first redundant load and the secondredundant load are configured identically, however it would be equallypossible to use a configuration in which equivalent functions arerealized by a combination of different devices. For example, the firstredundant load could be a LIDAR, for monitoring ahead of the vehicle,while the second redundant load could be a camera.

The first system ES1 includes a first current detector 401. The firstcurrent detector 401 is provided in an electrical path connecting thepositive electrode of the first power output section 11 to the firstpath ML1, and detects the output current of the first power outputsection 11 as a first output current Ir1. The second system ES2 includesa second current detector 402. The second current detector 402 isprovided in an electrical path connecting the positive electrode of thesecond power output section 12 to the second path ML2, and detects theoutput current of the second power output section 12 as a second outputcurrent Ir2. The detected values from the current detectors 401 and 402are inputted to a controller 500 that is included in the power supplysystem.

The controller 500 turns on or off the inter-system switch 100, theintra-system switches 201 and 202, and the individual switches 301A,301B, and 302. The controller 500 also performs engine combustioncontrol, etc. Each of these categories of control may actually beimplemented by respective controllers, however FIG. 1 shows thesecontrollers together in the form of a single controller 500. Thefunctions implemented by the controller 500 may be provided, forexample, by software that is recorded in a non-volatile memory deviceand a computer that executes the software, or by hardware, or by acombination thereof.

The controller 500 performs control for assisting the driver inoperating the steering wheel ST, by driving the electric power steeringapparatus. With the present embodiment, the electric power steeringdevice is divided into a first redundant load 31 and a second redundantload 32. As a result, even if an abnormality occurs in either one of thefirst redundant load 31 and the second redundant load 32, the otherredundant load can be used for control, so that a condition in whichsteering assistance suddenly becomes inoperative can be avoided. Inaddition, since the first power output section 11 and the second poweroutput section 12 are provided, power supply redundancy is ensured evenwhen an abnormality occurs in one of the power output sections, andhence the operational reliability of the first redundant load 31 and thesecond redundant load 32 can be improved.

It is possible that he output current of at least one of the first poweroutput section 11 and the second power output section 12 may becomeexcessively large. For example, when a ground fault occurs in which apart of a power supply system becomes short-circuited to ground, theoutput current may become excessively large. Even in such acircumstance, it is desirable to continue, as far as possible, to useany part of the power supply system that remains usable, for example toenable vehicle evacuation. Hence with the present embodiment, thecontroller 500 performs the abnormal operation processing shown in FIG.3.

In step S10, the first output current Ir1 and the second output currentIr2 are acquired. A decision is then made as to whether the acquiredfirst output current Ir1 or second output current Ir2 exceeds a firstthreshold value of current Ith1. For example, the first threshold valueof current Ith1 may be set to a value that is higher than the assumedmaximum value of the output current when a ground fault has notoccurred. With the present embodiment, the processing of step S10corresponds to a current judgement section.

If an affirmative decision is made in step S10, the processing proceedsto step S11, and the inter-system switch 100 is turned off. As a result,the first path ML1 and the second path ML2 become electricallydisconnected, and the first system ES1 and the second system ES2 becomeelectrically disconnected. With the present embodiment, the processingof step S11 corresponds to an inter-system operating section.

In step S12, a decision is made as to whether at least one of the firstoutput current Ir1 or the second output current Ir2 has become higherthan a second threshold value of current Ith2 which is higher than thefirst threshold value of current Ith1, by the time point at which afirst judgement interval Tα has elapsed since the inter-system switch100 was turned off. If a negative decision is made in step S12, theprocessing proceeds to step S21, and the inter-system switch 100 isturned on. A situation in which a negative decision is made in step S12may be, for example, a situation in which noise is superimposed on thefirst output current Ir1 or the second output current Ir2, and anaffirmative decision has been made in step S10.

If an affirmative decision is made in step S12, the processing proceedsto step S13. In step S13, each of the intra-system switch and theindividual switches provided in the target system are turned off, wherethe target system is the one of the first and second systems ES1 and ES2for which the output current has been judged to exceed the secondthreshold value of current Ith2. For example, if the target system isthe first system ES1, the first intra-system switch 201 and the first Aindividual switch 301A and first B individual switch 301B are turnedoff. All of the intra-system switches and individual switches in thefirst and second systems ES1 and ES2, other than the switches of thetarget system, remain turned on. For example, if the target system isthe first system ES1, the second intra-system switch 202 and the secondindividual switch 302 remain turned on. With the present embodiment, theprocessing of steps S12 and S13 corresponds to an intra-system operatingsection.

In step S14, the intra-system switch and the individual switches in thetarget system are sequentially turned on, starting from the one of theseswitches that is closest to the power output section. For example, ifthe target system is the first system ES1, then the first intra-systemswitch 201 is the first to be turned on. If the processing thereafterproceeds to step S14 after proceeding via steps S15 and S16, one of thefirst A and first B individual switches 301A and 301B is turned on. Ifthe processing then again proceeds to step S14 via steps S15 and S16,the other one of the first A and first B individual switches 301A and301B is turned on.

If a second judgement interval Tβ has elapsed since turning on of theswitches by executions of step S14 was completed, detection of the firstand second currents is performed in step S15. A decision is then made asto whether an output current Ir detected by a first or second currentdetector 401 or 402 provided in the target system exceeds the secondthreshold value of current Ith2.

If it is judged that the second threshold value of current Ith2 has notbeen exceeded before the second judgement interval Tβ elapsed, theprocessing proceeds to step S16, and a decision is made as to whetherall of the intra-system switches and individual switches provided in thetarget system have been turned on. If an affirmative decision is made instep S16, the processing proceeds to step S21. On the other hand, if anegative decision is made in step S16, the processing proceeds to stepS14, in which the next one of the intra-system switch and individualswitches that is required to be turned on, in the target system, is thenturned on. In the present embodiment, the processing of steps S14 andS16 corresponds to a first changeover operating section.

If it is judged in step S15 that the second threshold value of currentIth2 has been exceeded before the second judgement interval Tβ elapsed,the processing proceeds to step S17. In step S17, one of theintra-system switches and individual switches in the target system isspecified, where the specified switch is one of the intra-systemswitches and individual switches in the target system for which theoutput current Ir, detected by the current detector of the targetsystem, exceeded the second threshold value of current Ith2 when thatswitch was turned on in step S14. That switch is then registered in astorage device such as a memory provided in the controller 500. With thepresent embodiment, the processing of steps S15 and S17 corresponds to aspecifying section.

In step S18, all the intra-system switches and individual switches inthe target system are turned off. This prevents the output current ofthe power output section of the target system from becoming excessivelyhigh.

In step S19, a decision is made as to whether the switch specified instep S17 is an individual switch. If it is judged in step S19 that theswitch is an individual switch, the processing proceeds to step S20 inwhich, of the intra-system switches and individual switches in thetarget system, only the individual switch specified in step S17 isturned off, while the other switches are turned on. The inter-systemswitch 100 is then turned on in step S21. With the present embodiment,the processing of step S20 corresponds to a second changeover operatingsection.

If a negative decision is made in step S19, the processing proceeds tostep S22, and the off state of the inter-system switch 100 ismaintained.

If a ground fault occurs in the first path ML1 between the first poweroutput section 11 and the first intra-system switch 201, then even ifthe first intra-system switch 201 has been turned off, the outputcurrent of the first power output section 11 will continue to rise. Inthat case, the output of current from the first power output section 11may be interrupted by causing the first protection section 11 a that isprovided in the first power output section 11 to operate. Furthermore,it would be equally possible for the first protection section 11 aitself to detects its output current, and to operate when it is judgedthat the detected current exceeds the second threshold value of currentIth2, or for the first protection section 11 a to operate under thecontrol of the controller 500. It should also be noted that when thefirst protection section 11 a is provided in the first electric poweroutput section 11, it is not essential for the first intra-system switch201 to be provided in the first system ES1.

Moreover, if a ground fault occurs in the second path ML2 between thesecond power output section 12 and the second intra-system switch 202,then even if the second intra-system switch 202 is turned off, theoutput current of the second power output section 12 will continue torise. In that case, as with the first protection section 11 a, theoutput of current from the second power output section 12 can beinterrupted by operating the second protection section 12 a that isincluded in the second power output section 12. It should be noted thatwhen the second protection section 12 a is provided in the second poweroutput section 12, it is not essential for the second intra-systemswitch 202 to be provided in the second system ES2.

FIGS. 4 and 5 show an example of the operation processing executed whenan abnormality occurs. Firstly, FIG. 4 shows a case in which a groundfault has occurred between the positive electrode of the first redundantload 31 and the first A individual switch 301A, in the first system ES1.FIG. 4(a) shows the transitions of first and second output currents Ir1and Ir2, and FIGS. 4(b) to (e) shows the transitions of the operationstates of the inter-system switch 100, the first intra-system switch201, and the first A and first B individual switches 301A and 301B.

At time t1, a ground fault occurs at the location described above. As aresult, a high level of current begins to flow from the first poweroutput section 11 and the second power output section 12 toward theground fault location, and the first and second output currents Ir1 andIr2 begin to rise. At time t2, the first output current Ir1 exceeds thefirst threshold value of current Ith1. As a result, the inter-systemswitch 100 is turned off, thereby disconnecting the second system ES2from the first system ES1 in which a ground fault has occurred. As aresult, the increase in the second output current Ir2 is halted.Moreover, the second system ES2, which is functioning normally and inwhich no ground fault has occurred, continues to be used.

Thereafter, the first output current Ir1 continues to rise. The firstoutput current Ir1 exceeds the second threshold value of current Ith2 attime t3, before the first judgement interval Tα has elapses after theinter-system switch 100 was turned off. As a result, the firstintra-system switch 201 and the 1A and 1B individual switches 301A and301B are turned off. The first output current Ir1 thereby decreasestoward zero.

At time t4 the first intra-system switch 201, which is the switch thatis closest to the first power output section 11 among the firstintra-system switch 201 and the first A and first B individual switches301A and 301B, is turned on. Even if the second judgement interval Tβhas elapsed after the first intra-system switch 201 was turned on, thefirst output current Ir1 will not exceed the second threshold value ofcurrent Ith2. Hence at time t5, the switch that is closest to the firstpower output section 11, among the first intra-system switch 201 and thefirst A and first B individual switches 301A and 301B, is turned on.With the present embodiment, the next closest switches are the first Aindividual switch 301A and the first B individual switch 301B. Hence, ofthe individual switches 301A and 301B, the first A individual switch301A, which is connected to a redundant load, is turned on. As a result,when a condition has arisen whereby the second redundant load 32 of thesecond system ES2 has become unusable, during a period in which aspecified switch has caused an overcurrent to flow in the first systemES1, the first power output section 11 can supply power to the firstredundant load 31 with priority over supplying power to the normal load21.

When the first A individual switch 301A is turned on, the first outputcurrent starts to rise. Thereafter, the first output current Ir1 exceedsthe second threshold value of current Ith2 at time t6, before the secondjudgement interval Tβ has elapsed after the first A individual switch301A was turned on. As a result, of the first intra-system switch 201and the first A and the first B individual switches 301A and 301B, thefirst A individual switch 301A is specified and registered as being theswitch that has caused the first output current Ir1 to exceed the secondthreshold value of current Ith2. Furthermore, the first intra-systemswitch 201 and the first A individual switch 301A are again turned off.With the present embodiment the 1A individual switch 301A, which hasbeen specified and registered, is not turned on thereafter.

At time t7, the first intra-system switch 201 is turned on, and at timet8, the first B individual switch 301B is turned on. At time t9, theinter-system switch 100 is turned on.

It should be noted that of the first intra-system switch 201 and thefirst A individual switch 301A, it would be equally possible for onlythe first A individual switch 301A, which has been specified, to beturned off again at time t6.

Next, FIG. 5 shows a case in which a ground fault has occurred in thefirst system ES1, on the first path ML1 between the inter-system switch100 and the first intra-system switch 201. FIGS. 5(a) to 5(e) correspondto the previous FIGS. 4(a) to 4(e).

At time t1, a ground fault occurs at the above-described location, andat time t2, the first output current Ir1 exceeds the first thresholdvalue of current Ith1. As a result, the inter-system switch 100 isturned off. Thereafter, the first output current Ir1 exceeds the secondthreshold value of current Ith2 at a time t3, before the first judgementinterval Tα has elapsed after the inter-system switch 100 was turnedoff. As a result, the first intra-system switch 201 and the 1A and 1Bindividual switches 301A and 301B are turned off.

At time t4 the first intra-system switch 201, which is the closestswitch to the first power output section 11, is turned on. Thereafter,the first output current Ir1 exceeds the second threshold value ofcurrent Ith2 at time t5, before the second judgement interval Tβ haselapsed after the first intra-system switch 201 was turned on. Hence, ofthe first intra-system switch 201 and the first A and the first Bindividual switches 301A and 301B, the first intra-system switch 201 isspecified and registered as the switch that has caused the first outputcurrent Ir1 to exceed the second threshold value of current Ith2.Furthermore, the first intra-system switch 201 is turned off again. Withthe present embodiment, the first intra-system switch 201, which hasbeen registered, is not turned on thereafter. In addition, theinter-system switch 100 is maintained in the off state.

With the present embodiment described above, even if a ground faultoccurs in either of the first and second systems ES1 and ES2, the poweroutput section and the load (s) that constitute the system in which theground fault has occurred can continue to be used as far as possible. Alowering of the reliability of the power supply system can thereby besuppressed.

Modification Example of First Embodiment

In FIG. 3, the processing of steps S12 to S22 may be omitted. Even inthat case it is possible to protect the one of the first and secondsystems ES1, ES2 in which no ground fault has occurred, and to continueusing that system.

In FIG. 3, the processing of steps S14 to S22 may be omitted. Even inthat case, it is possible to avoid an overcurrent from being producedfrom the power output section of the target system, and thus to protectthat power output section.

Second Embodiment

A second embodiment will be described referring to the drawings with afocus on points of difference from the first embodiment. With thepresent embodiment, as illustrated in FIG. 6, a power supply systemincludes a voltage detector instead of the current detector. In FIG. 6,components that are identical to those shown in FIG. 1 are designated bythe same reference numerals as in FIG. 1, for convenience.

The first system ES1 includes a first voltage detector 411. The firstvoltage detector 411 detects the output voltage of the first poweroutput section 11, as the first output voltage Vr1. The second systemES2 includes a second voltage detector 412. The second voltage detector412 detects the output voltage of the second power output section 12, asthe second output voltage Vr2. The detection values from the voltagedetectors 411 and 412 are inputted to the controller 500.

The processing executed by the present embodiment when an abnormalityoccurs will be described referring to FIG. 7. This processing isexecuted by the controller 500. In FIG. 7, processing steps that areidentical to those shown in FIG. 3 are designated by the same referencenumerals as in FIG. 3, for convenience.

In step S23, the first output voltage Vr1 and the second output voltageVr2 are acquired. A decision is then made as to whether the acquiredfirst output voltage Vr1 or second output voltage Vr2 is lower than thefirst voltage threshold value Vth1. This processing is based on the factthat when a ground fault occurs, the amount of lowering of the outputvoltage increases as the output current increases. With the presentembodiment, the processing of step S23 corresponds to a voltagejudgement section.

If an affirmative decision is made in step S23, the processing proceedsto step S24 via step S11. In step S24, a decision is made as to whetherthe first output voltage Vr1 or the second output voltage Vr2 is below asecond voltage threshold value Vth2, which is lower than the firstvoltage threshold value Vth1. If an affirmative decision is made in stepS24, the processing proceeds to step S13. In step S13, one of the firstand second systems ES1 and ES2, for which it has been judged that theoutput voltage is lower than the second voltage threshold value Vth2, isset as the target system.

After the processing of step S14 is completed, the processing proceedsto step S25, in which a decision is made as to whether the outputvoltage Vr detected by the one of the first and second voltage detectors411 and 412 provided in the target system has become lower than thesecond voltage threshold value Vth2 during the interval which elapsedfrom the time when a switch is turned on in step S14 until the secondjudgement interval Tβ elapsed.

If an affirmative decision is made in step S25, the processing proceedsto step S17. In step S17 one of the switches in the target system isspecified, where the specified switch is the one of the intra-systemswitches and individual switches in the target system for which theoutput voltage Vr detected by the voltage detector of the target systemwas lower than the second voltage threshold value Vth2, when that switchwas turned on in step S14.

The same effects as those of the first embodiment can be obtained withthe embodiment described above.

Third Embodiment

A third embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. With the present embodiment, as shown in FIG. 8, a powersupply system is provided with fuses, instead of the individualswitches. In FIG. 8, configuration components that are identical tothose shown in FIG. 1 above are designated by the same referencenumerals as in FIG. 1, for convenience.

A first A fuse 311A is provided in place of the first A individualswitch 301A, a first B fuse 311B is provided in place of the first Bindividual switch 301B, and a second fuse 312 is provided in place ofthe second individual switch 302. For example, current will continue toflow through each of the fuses 311A, 311B and 312 even if the firstthreshold value of current Ith1 is exceeded, however a fuse will becomeblown before the current flowing through that fuse exceeds the secondthreshold value of current Ith2. If the second fuse 312 is blown, forexample, then the second redundant load 32 will become disconnected fromthe second path ML2.

With the present embodiment, when a ground fault occurs between a fuse311A, 311B or 312 and the respective one of the loads 31, 21, 32, thefuse that is connected to the location where the ground fault occursbecomes blown. As a result, unlike the first embodiment, it is notnecessary to again turn on those of the individual switches which do notcorrespond to the location where the ground fault occurred.

On the other hand, when a ground fault occurs on the first path ML1between the inter-system switch 100 and the first intra-system switch201, or when a ground fault occurs on the second path ML2 between theinter-system switch 100 and the second intra-system switch 202 t, thefirst intra-system switch 201 or the second intra-system switch 202 mustbe operated. In view of this, the controller 500 performs the abnormaloperation processing shown in FIG. 8. In FIG. 8, processing steps thatare identical to those shown in FIG. 3 are designated by the samereference numerals as in FIG. 3, for convenience

After completion of the processing of step S11, the processing proceedsto step S30, in which a decision is made as to whether the first outputcurrent Ir1 or the second output current Ir2 has increased even afterthe third predetermined time Tγ elapsed since the inter-system switch100 was turned off in step S11. This processing serves to determinewhether a ground fault has occurred in the first path ML1 between theinter-system switch 100 and the first intra-system switch 201, or in thesecond path ML2 between the inter-system switch 100 and the secondintra-system switch 202. The first system ES1 will be described as anexample. If a ground fault occurs between the first redundant load 31and the first A fuse 311A, the first A fuse 311A will be blown when acertain amount of time has elapsed after the ground fault occurred, andhence the first output current Ir1 will not increase, and will start todecrease. On the other hand if a ground fault occurs in the first pathML1 between the inter-system switch 100 and the first intra-systemswitch 201, then neither the first A fuse 311A nor the first B fuse 311Bwill be blown, and hence the first output current Ir1 will continue torise.

With the present embodiment, the one of the first and second systems ES1and ES2 in which the output current continues to increase is made thetarget system.

If an affirmative decision is made in step S30, the processing proceedsto step S31, in which the intra-system switch of the target system isturned off. For example, if the target system is the first system ES1,the first intra-system switch 201 is turned off. This prevents a highlevel of current flow from the power output section of the targetsystem.

If a negative decision is made in step S30, the processing proceeds tostep S32, in which the inter-system switch 100 is turned on. In thatcase, in the target system, the fuse corresponding to the ground faultlocation will become blown.

The present embodiment described above enables simplification of thecontents of operation processing that is executed when an abnormalityoccurs.

Modification Example 1 of Third Embodiment

With the configuration shown in FIG. 8, the first and secondintra-system switches 201 and 202 may be omitted.

Modification Example 2 of Third Embodiment

With the configuration shown in FIG. 8, the first and second voltagedetectors 411 and 412 shown in FIG. 6 may be provided in place of thefirst and second current detectors 401 and 402. The abnormal operationprocessing that is executed by the controller 500 in that case will bedescribed referring to FIG. 10. In FIG. 10, processing steps that areidentical to those shown in FIG. 7 are designated by the same referencenumerals as in FIG. 7, for convenience.

If an affirmative decision is made in step S23, the processing proceedsto step S33 via step S11. In step S33, a decision is made as to whetherthe first output voltage Vr1 or the second output voltage Vr2 continuesto decrease even after the third predetermined time Tγ has elapsed sincethe inter-system switch 100 was turned off in step S11. This processingstep is provided for the same purpose as step S30 in FIG. 9. With thepresent embodiment, the target system is taken to be the one of thefirst and second systems ES1 and ES2 for which the output voltage isjudged to continue to decrease.

If an affirmative decision is made in step S33, the processing proceedsto step S31. On the other hand, if a negative decision is made in stepS33, the processing proceeds to step S32.

Fourth Embodiment

A fourth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. FIG. 11 shows a power supply system of the presentembodiment. In FIG. 11, configuration components that are identical tothose shown in FIG. 1 above are designated by the same referencenumerals as in FIG. 1, for convenience. With the present embodiment, thenormal load 21 is a first normal load, the first redundant load 31 is afirst A redundant load 31A, and the second redundant load 32 is a secondA redundant load 32A.

The first system ES1 includes a first B redundant load 31B. The secondsystem ES2 includes a second normal load 22 and a second B redundantload 32B. With the present embodiment, the first B redundant load 31Band the second B redundant load 32B consist of in-vehicle cameras thatcapture images of the road ahead of the host vehicle. Detectioninformation from the first B redundant load 31B and the second Bredundant load 32B is inputted to the controller 500.

The first system ES1 includes first A to C individual switches 301A to301C. The second system ES2 includes second A to C intra-system switches202A to 202C and second A to C individual switches 302A to 302C. Each ofthe switches 301A to 301C, 202A to 202C, and 302A to 302C is constitutedby a semiconductor switch such as a relay or a MOS FET, for example.Each of the switches of the systems ES1, ES2 is operated by thecontroller 500.

Between the inter-system switch 100 and the first intra-system switch201, the first path ML1 is connected via the first A individual switch301A to the positive electrode of the first A redundant load 31A, and isconnected via the first B individual switch 301B to the positiveelectrode of the first B redundant load 31B, and also is connected viathe first C individual switch 301C to the positive electrode of thefirst normal load 21.

The second path ML2 is provided with a second A intra-system switch202A, a second B intra-system switch 202B, and a second C intra-systemswitch 202C disposed successively from the side closer to the secondpower output section 12. In the second path ML2, the positive electrodeof the second A redundant load 32A is connected between the second Aintra-system switch 202A and the second B intra-system switch 202B viathe second A individual switch 302A. A part of the second path ML2 thatis sandwiched between the second B intra-system switch 202B and thesecond C intra-system switch 202C is connected to the positive electrodeof the second B redundant load 32B via the second B individual switch302B. A part of the second path ML2 between the inter-system switch 100and the second C intra-system switch 202C is connected to the positiveelectrode of the second normal load 22 via the second C individualswitch 302C.

The controller 500 in conjunction with the redundant loads 31A, 32A,31B, 32B constitutes a lane keeping support system. This systemrecognizes the travel lane of the host vehicle, on the road, from thedetection information of the first A redundant load 31A and the first Bredundant load 31B, which are in-vehicle cameras, and when the hostvehicle is about to depart from the travel lane, steering control iseffected by torque assistance of the electric power steering device, formoving the vehicle back to the center of the travel lane. By providingtwo in-vehicle cameras, even if an abnormality occurs in the first Aredundant load 31A or the first B redundant load 31B, the detectioninformation of the other can be used for effecting control, and the hostvehicle can be maintained within its travel lane, so that a sudden lossof lane keeping support control can be avoided.

The main points of difference between the abnormal operation processingof the present embodiment and that of the first embodiment will bedescribed in the following referring to FIG. 12. In FIG. 12, processingsteps which are identical to those shown in FIG. 3 are designated by thesame reference numerals as in FIG. 3, for convenience. A case in which aground fault occurs in the second system ES2 will be described in thefollowing, as an example.

In step S14, the switches are sequentially turned on, starting from theswitch that is closest to the second power output section 12.Specifically, the second A intra-system switch 202A, the second Aindividual switch 302A, the second B intra-system switch 202B, thesecond B individual switch 302B, the second C intra-system switch 202C,and the second C individual switch 302C are turned on, in that order.

If a negative decision is made in step S19, the processing proceeds tostep S40, and the switch operation processing shown in FIG. 13 isperformed.

In step S41 a decision is made as to whether the switch specified instep S17 is one of the switches in the second system ES2.

If an affirmative decision is made in step S41, the processing proceedsto step S42, and a decision is made as to whether any of theintra-system switches 202A to 202C has been specified in step S17, otherthan the second C intra-system switch 202C, which is closest to theinter-system switch 100.

If an affirmative decision is made in step S42, the processing proceedsto step S43, in which the one of the intra-system switches 202A to 202Cthat has been specified, and one of these intra-system switches that isadjacent to the specified intra-system switch on the inter-system switch100 side, are maintained turned off. Furthermore, the one of theintra-system switches 202A to 202C that is not maintained turned off,the inter-system switch 100, and the second C individual switch 302C,which is the individual switch closest to the inter-system switch 100,are turned on. In addition, those of the individual switches 302A to302C that are adjacent to the intra-system switch which has been turnedon are also turned on.

For example if the specified intra-system switch is the second Aintra-system switch 202A, then the second A intra-system switch 202A andthe second B intra-system switch 202B, which are adjacent to the switch202A, are maintained in the off state, while the second C intra-systemswitch 202C, the inter-system switch 100, and the second B and Cindividual switches 302B and 302C, which are respectively adjacent tothe second C intra-system switch 202C, are turned on. The second normalload 22 and the second B redundant load 32B can thereby continue to beused, employing the first power output section 11 as a power supplysource.

Also, for example, if the specified intra-system switch is the second Bintra-system switch 202B, the second B intra-system switch 202B and thesecond C intra-system switch 202C, which is adjacent to the switch 202B,are maintained in the off state. Furthermore, the second A intra-systemswitch 202A, the inter-system switch 100, and the second A and Cindividual switches 302A and 302C are turned on. The second A redundantload 32A can thereby continue to be used, employing the second poweroutput section 12 as a power supply source, and the second normal load22 can continue to be used, employing the first power output section 11as a power supply source.

If a negative decision is made in step S42, the processing proceeds tostep S44, in which a decision is made as to whether the second Cintra-system switch 202C, which is closest to the inter-system switch100 among the intra-system switches 202A to 202C, has been specified instep S17.

If an affirmative decision is made in step S44, the processing proceedsto step S45, in which the specified second C intra-system switch 202Cand the inter-system switch 100 are maintained in the off state. Also,of the switches of the second system ES2, those of the second A and Bintra-system switches 202A and 202B that are not being maintained turnedoff, and the second A and B individual switches 302A and 302B, which areadjacent to the switches 202A and 202B, are turned on. The second Aredundant load 32A and the second B redundant load 32B can therebycontinue to be used, employing the second power output section 12 as apower supply.

With the embodiment described above, the same effects can be obtained asfor the first embodiment.

Modification Example of the Fourth Embodiment

The position of the inter-system switch 100 in the power supply systemis determined by a balance between the capacities of the respectivepower output sections of the systems ES1, ES2 and the power consumptionamounts of the respective loads. Hence, depending on this balance, theposition of the inter-system switch 100 shown in FIG. 11 may be made asshown in FIG. 14, for example. In FIG. 14, components which areidentical to components shown in FIG. 11 are designated by the samereference numerals as in FIG. 11, for convenience.

Fifth Embodiment

The fifth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. With the present embodiment, as shown in FIG. 15, a powersupply system includes three power systems consisting of first to thirdsystems ES1 to ES3. In FIG. 15, components which are identical tocomponents shown in FIG. 1, etc., are designated by the same referencenumerals as in FIG. 1, for convenience.

The power supply system includes a third path ML3, a first inter-systemswitch 111, and a second inter-system switch 112. The third system ES3includes a third intra-system switch 203 and a third individual switch303. Each of the switches 111, 112, 203, and 303 is configured as asemiconductor switch such as a relay or a MOS FET, for example. Each ofthe switches 111, 112, 203, 303 is operated by the controller 500.

The second path ML2 is connected to the first path ML1 via the firstinter-system switch 111. The third path ML3 is connected to the secondpath ML2 via the second inter-system switch 112. In the second path ML2,the second A intra-system switch 202A is provided on the secondinter-system switch 112 side and the second B intra-system switch 202Bis provided on the first inter-system switch 111 side. In the secondpath ML2, on the side of the first inter-system switch 111, the positiveelectrode of the second redundant load 32 is connected to the second Bintra-system switch 202B via the second A individual switch 302A. Thepositive electrode of the second normal load 22 is connected to thesecond path ML2 between the second B intra-system switch 202B and thesecond A intra-system switch 202A, via the second B individual switch302B. The positive electrode of the second power output section 12 isconnected via the second current detector 402 to the second path ML2between the second inter-system switch 112 and the second B intra-systemswitch 202A.

The third system ES3 includes a third power output section 13, and athird current detector 403 which detects the output current of the thirdpower output section 13 as a third output current Ir3. The third outputcurrent Ir3 is inputted to the controller 500. The third power outputsection 13 is, for example, a secondary battery, as for the first andsecond power output sections 11 and 12. A third intra-system switch 203is provided in the third path ML3. The positive electrode of the thirdnormal load 23 is connected via the third current detector 403 to thethird path ML3, on the second inter-system switch 112 side, via thethird individual switch 303. The positive electrode of the third poweroutput section 13 is connected via the third current detector 403 to thethird path ML3 on the side opposite the second inter-system switch 112with respect to the third intra-system switch 203.

The main differences between the abnormal operation processing of thepresent embodiment and that of the first embodiment will be described inthe following. With the present embodiment, the first to third outputcurrents Ir1 to Ir3 are used in the processing executed in steps S10,S12, and S15 of FIG. 3. Specifically, the processing of step S10 isreplaced by processing for judging whether any of the first to thirdoutput currents Ir1 to Ir3 exceeds the first threshold value of currentIth1. Furthermore, the processing of step S12 is replaced by processingfor judging whether any of the first to third output currents Ir1 to Ir3exceeds the second threshold value of current Ith2. Moreover theprocessing of step S15 is replaced by processing for judging whether,during the interval from the time at which a switch was turned on instep S14 until the second judgement interval Tβ has elapsed, the outputcurrent Ir detected by the one of the first to third current detectors401 to 403 that is provided in the target system has exceeded the secondthreshold value of current Ith2.

The present embodiment described above can provide the same effects asthose of the first embodiment.

Modification Example 1 of the Fifth Embodiment

It should be noted that a third redundant load, which constitutes theelectric power steering device in conjunction with the first and secondredundant loads 31 and 32, may be provided in the third system ES3 inplace of the third normal load 23. Each system is thereby provided witha redundant load.

Modification Example 2 of the Fifth Embodiment

In the configuration shown in FIG. 15, it would be equally possible toprovide a voltage detector that detects the output voltage of each poweroutput section, as in FIG. 6, instead of the current detectors 401 to403.

Sixth Embodiment

A sixth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. With this embodiment, as shown in FIG. 16, the power systemsform a ring configuration. In FIG. 16, components which are identical tocomponents shown in FIG. 1, etc., are designated by the same referencenumerals as in FIG. 1, etc., for convenience.

A power supply system includes a first path MLα, a second path MLβ, afirst inter-system switch 121, and a second inter-system switch 122. Afirst end of the second path MLβ is connected to a first end of thefirst path MLα via the first inter-system switch 121. The second end ofthe second path MLβ is connected to the second end of the first path MLαvia the second inter-system switch 122. As a result, the power systemhas the form of a ring.

The first system ES1 includes first A and B intra-system switches 211Aand 211B, first A to D individual switches 321A to 321D, first A and Bnormal loads 21A and 21B, and a first redundant load 31. In the firstpath MLα, a first B intra-system switch 211B is provided on the firstinter-system switch 121 side, and a first A intra-system switch 211A isprovided on the second inter-system switch 122 side. The positiveelectrode of the first redundant load 31 is connected via the first Dindividual switch 321D to the part of the first path MLα that is betweenthe first inter-system switch 121 and the first B intra-system switch211B. The positive electrode of the first power output section 11 isconnected via the first A individual switch 321A and the first currentdetector 401 to the part of the first path MLα that is between the firstB intra-system switch 211B and the first A intra-system switch 211A. Thepositive electrodes of the first A normal load 21A and the first Bnormal load 21B are connected via the first B individual switch 321B andthe first C individual switch 321C to the part of the first path MLαbetween the second inter-system switch 122 and the first intra-A systemswitch 211A.

The second system ES2 includes second A and B intra-system switches 212Aand 212B, second A to C individual switches 322A to 322C, a secondnormal load 22, and a second redundant load 32. In the second path MLβ,the second B intra-system switch 212 is provided on the firstinter-system switch 121 side, and the second-A intra-system switch 212is provided on the second inter-system switch 122 side. The positiveelectrode of the second redundant load 32 is connected via the second Cindividual switch 322C to the part of the second path MLβ between thefirst inter-system switch 121 and the second B intra-system switch 212B.The positive electrode of the second power output section 12 isconnected via the second A individual switch 322A and the second currentdetector 402 to the part of second path MLβ that is between the second Bintra-system switch 212B and the second A intra-system switch 212A. Inthe second path MLβ, the positive electrode of the second normal load 22is connected between the second inter-system switch 122 and the second Aintra-system switch 212A via a second B individual switch 322B.

With the present embodiment described above, since the power systemsform a ring configuration, the location where a ground fault occurs canbe readily distinguished.

Seventh Embodiment

A seventh embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the sixthembodiment. With this embodiment, as shown in FIG. 17, the power systemsform a ring configuration. In FIG. 17, components which are identical tocomponents shown in FIG. 16, etc., are designated by the same referencenumerals as in FIG. 16, etc., for convenience.

A power supply system includes first to fourth paths MLa to MLd andfirst to fourth inter-system switches 131 to 134. The first end of thesecond path MLb is connected to the first end of the first path MLa viathe first inter-system switch 131. The first end of the third path MLcis connected to the second end of the second path MLb via the secondinter-system switch 132. The first end of the fourth path MLd isconnected to the second end of the third path MLc via the thirdinter-system switch 133. The first end of the first path MLa isconnected to the second end of the fourth path MLd via the fourthinter-system switch 134. The power systems thus have the form of a ring.

The first system ES1 includes first A and B intra-system switches 221Aand 221B, and first A to C individual switches 331A to 331C. In thefirst path MLa, the first A intra-system switch 221A is provided on theside of the first inter-intra-system switch 131, and the first Bintra-system switch 221B is provided on the side of the fourthinter-intra-system switch 134. The positive electrode of the first poweroutput section 11 is connected via the first A individual switch 331Aand the first current detector 401 to the first path MLa on the firstinter-intra-system switch 131 side of the first A intra-system switch221A. The positive electrode of the first redundant load 31 is connectedvia the first B individual switch 331B to the first path MLa between thefirst A intra-system switch 221A and the first B intra-system switch221B. The positive electrode of the first normal load 21 is connectedvia the first C individual switch 331C to the first path MLa between thefourth inter-intra-system switch 134 and the first intra-B intra-systemswitch 221B.

The second system ES2 includes a second intra-system switch 222 andsecond A and B individual switches 332A and 332B. In the second pathMLb, the positive electrode of the second power output section 12 isconnected to the first inter-system switch 131 side of the secondintra-system switch 222 via the second A individual switch 332A and thesecond current detector 402. In the second path MLb, the positiveelectrode of the second normal load 22 is connected to the secondinter-system switch 132 side of the second intra-system switch 222 viathe second B individual switch 332B.

The third system ES3 includes a third intra-system switch 223 and thirdA and B individual switches 333A and 333B. The positive electrode of thethird power output section 13 is connected via the third A individualswitch 333A and the third current detector 403 to the third path MLc onthe second inter-system switch 132 side of the third intra-system switch223. The positive electrode of the third normal load 23 is connected viathe third B individual switch 333B to the third path MLc on the thirdinter-system switch 133 side of the third intra-system switch 223.

The fourth system ES4 includes fourth A and B intra-system switches 224Aand 224B, and fourth A to C individual switches 334A to 334C. In thefourth path MLd, a fourth A intra-system switch 224A is provided on thefourth inter-system switch 134 side, and a fourth B intra-system switch224B is provided on the third inter-system switch 133 side. The positiveelectrode of the fourth power output section 14 is connected via thefourth A individual switch 334A and the fourth current detector 404 tothe fourth path MLd between the fourth inter-system switch 134 and thefourth A intra-system switch 224A. The fourth current detector 404detects the output current of the fourth power output section 14, as thefourth output current Ir4. The fourth output current Ir4 is inputted tothe controller 500. The fourth power output section 14 is, for example,a secondary battery, as for the first to third power output sections 11to 13. The positive electrode of the second redundant load 32 isconnected via the fourth B individual switch 334B to the fourth path MLdbetween the fourth A intra-system switch 224A and the fourth Bintra-system switch 224B. The positive electrode of the fourth normalload 24 is connected via the fourth C individual switch 334C to thefourth path MLd between the fourth intra-inter-system switch 224B andthe third inter-system switch 133.

The operation processing executed when an abnormality occurs with thepresent embodiment will be described in the following.

When for example a ground fault occurs in the second path MLb, thecontroller 500 turns off the first to fourth inter-system switches 131to 134. Thereafter, the controller 500 judges that, except for thesecond system ES2 which is the target system, the systems ES1 to ES4 ofthe systems ES1, ES3, and ES4 can be brought into a conductive state viathe inter-system switches 133 and 134. As a result, as shown in FIG. 18,the controller 500 maintains the first inter-system switch 131 and thesecond inter-system switch 132 in the off state, and turns on the thirdinter-system switch 133 and the fourth inter-system switch 134. Thesecond system ES2, in which the ground fault has occurred, can therebybe disconnected from the first, third and fourth system ES1, ES3, ES4.

With the present embodiment described above, the same effects can beobtained as for the sixth embodiment.

Modification Example 1 of the Seventh Embodiment

A first B redundant load 31B which constitutes a vehicle-mounted cameramay be provided in the second system ES2, with the first redundant load31 which constitutes an electric power steering device being omitted.Furthermore, a second B redundant load 32B which constitutes avehicle-mounted camera may be provided in the third system ES3, with thesecond redundant load 32 which constitutes an electric power steeringdevice being omitted. Since the devices used for effecting lane keepingsupport control as common control are disposed distributed among thesystems ES1 to ES4 respectively, the reliability of lane keeping supportcontrol can be improved.

Modification Example 2 of the Seventh Embodiment

As shown in FIG. 19, first to fourth voltage detectors 411 to 414 thatdetect the output voltages of the first to fourth power output sections11 to 14 may be provided in place of the first to fourth currentdetectors 401 to 404 of the configuration shown in FIG. 17. With thisconfiguration also, for example as shown in FIG. 18, a system in which aground fault has occurred can be disconnected from the other systems.

Eighth Embodiment

An eighth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. With the present embodiment, as shown in FIG. 20, the firstsystem ES1 is provided with a storage battery and an alternator as powersupplies. In FIG. 20, components which are identical to components shownin FIG. 1 etc., above, are designated by the same reference numerals asin FIG. 1 etc., for convenience.

The first system ES1 includes a first storage battery 41 as a firstpower output section, an alternator 600, first A and B intra-systemswitches 231A and 231B, and first A and B current detectors 401A and401B. The first A current detector 401A detects the output current fromthe first storage battery 41 as the first A output current I1 a. Thefirst B current detector 401B detects the output current from thealternator 600 as the first B output current I1 b. The first A and Boutput currents I1 a and I1 b are inputted to the controller 500. Thesecond system ES2 includes a second storage battery 42 as a second poweroutput section. With the present embodiment, the storage batteries 41and 42 have the same rated voltage (for example 12V). Each storagebattery 41, 42 is, for example, a lead-acid storage battery.

A first B intra-system switch 231B is provided in the first path ML1, onthe inter-system switch 100 side, and a first A intra-system switch 231Ais provided in the first path ML1 n on the opposite side from theinter-system switch 100. The output side of the alternator 600 isconnected to the first path ML1 between the first A system switch 231Aand the first B system switch 231B, via the fuse 311C and the first Bcurrent detector 401B. The positive electrode of the first storagebattery 41 is connected via the first A current detector 401A to thefirst path ML1 at the opposite side of the first A intra-system switch231A from the first B intra-system switch 231B.

The alternator 600 performs electrical generation by being supplied withpower from the output shaft of the engine 700 that is mounted on thevehicle, and outputs current. The output current of the alternator 600can charge the first storage battery 41 and the second storage battery42, and can supply power to the loads 21, 31, 32. With the presentembodiment, power generation by the alternator 600 is controlled by thecontroller 500.

The main points of difference of the abnormal operation processing ofthe present embodiment from that of the first embodiment will bedescribed in the following.

The first A and B output currents I1 a and I1 b and the second outputcurrent Ir2 are used in steps S10, S12, and S15 of FIG. 3.

The case in which a ground fault has occurred in the first system ES1will be described as an example. In step S14, the first A intra-systemswitch 231A and the first B intra-system switch 231B are successivelyturned on, in that order. One of the first A and B individual switches301A and 301B is subsequently turned on, and then the other is turnedon.

The present embodiment described above can provide the same effects asthose of the first embodiment.

Ninth Embodiment

A ninth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the firstembodiment. With the present embodiment, as shown in FIG. 21, the firstsystem ES1 is provided with a DC-DC converter 51 that outputs power froman in-vehicle high voltage storage battery 800, as a power supply. Thehigh voltage storage battery 800 corresponds to a high-voltage sidestorage device, and the second storage battery 42 corresponds to alow-voltage side storage device. In FIG. 21, components which areidentical to components shown in FIGS. 1 and 20 are designated by thesame reference numerals, for convenience.

The high voltage storage battery 800 has a higher rated voltage (forexample, several hundred volts) than the second storage battery 42, andis, for example, a lithium-ion storage battery. A rotary electricalmachine 900 is connected to the high voltage storage battery 800. Therotary electrical machine 900 is a main in-vehicle machine, which issupplied with electrical power from the high voltage storage battery 800and transmits mechanical power to drive the road wheels.

A power supply system includes a DC-DC converter 51. The DC-DC converter51 includes a first connection section 51A and a second connectionsection 51B. The first connecting portion 51A is connected in parallelwith the high voltage storage battery 800. to the positive electrodeside of the second connection section 51B is connected via the firstcurrent detector 401 to the first path ML1, and the negative electrodeside. is connected to ground. The DC-DC converter 51 has a voltagestep-down function of stepping down the DC voltage that is inputted fromthe first connection section 51A and outputting that DC voltage from thesecond connection section 51B, and a voltage boosting function ofstepping up the DC voltage that is inputted from the second connectionsection 51B and outputting that DC voltage from the first connectionsection 51A. The DC-DC converter 51 is controlled by the controller 500.It should be noted that even after the power supply on the first systemES1 side has become disconnected, it would be possible for the controlpower supply of the DC-DC converter 51 to receive power from the highvoltage storage battery 800 side that has been separately stepped downin voltage, or to receive power from the power system on the secondsystem ES2 side, etc.

The embodiment described above can provide the same effects as those ofthe first embodiment.

Tenth Embodiment

A tenth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the ninthembodiment. With the present embodiment, the configuration of a powersupply system is changed as shown in FIG. 22. In FIG. 22, componentswhich are identical to components shown in FIG. 21, etc., are designatedby the same reference numerals as in FIG. 21, etc., for convenience. Inthe following, the controller 500 is omitted from the drawings.

The second system ES2 includes an alternator 600. The second path ML2 isconnected to the output side of the alternator 600. The first path ML1is connected to the second path ML2 via a first inter-system switch 141.The positive electrode of the second storage battery 42 is connected tothe part of the second path ML2 that is between a second A intra-systemswitch 232A and a second B intra-system switch 232B.

The power supply system includes a first intermediate-voltage system EM1and a second intermediate-voltage system EM2, as power systems. Thepower supply system includes a first intermediate-voltage path MM1 and asecond intermediate-voltage path MM2, as electrical paths.

The first intermediate-voltage system EM1 includes a firstintermediate-voltage intra-system switch 251, a firstintermediate-voltage individual switch 351, an intermediate-voltagestorage battery 91 as a power output section, an intermediate-voltageload 61 as an electrical load, and a first intermediate-voltage currentdetector 421. The intermediate-voltage storage battery 91 has a highervalue of rated voltage (for example, 48 V) than the second storagebattery 42. The first intermediate-voltage current detector 421 detectsthe output current of the intermediate-voltage storage battery 91 andoutputs the value of that current to the controller 500. With thepresent embodiment, the intermediate-voltage storage battery 91corresponds to a high-voltage side storage device, and the secondstorage battery 42 corresponds to a low-voltage side storage device.

The second intermediate-voltage system EM2 includes a secondintermediate-voltage intra-system switch 252, a secondintermediate-voltage individual switch 352, a secondintermediate-voltage load 62, an intermediate-voltage rotary electricalmachine 63 as a power output section, and a second intermediate-voltagecurrent detector 422. The intermediate-voltage rotary electrical machine63 generates electric power by being supplied with power from the outputshaft of the engine 700, and outputs a current. The output current ofthe intermediate-voltage rotary electrical machine 63 can charge theintermediate-voltage storage battery 91, or can supply power to each ofthe intermediate-voltage loads 61 and 62. Furthermore, theintermediate-voltage rotary electrical machine 63 can be driven as anelectric motor by being supplied with power. The secondintermediate-voltage current detector 422 detects the output current ofthe intermediate-voltage rotary electrical machine 63, and outputs thevalue of the current to the controller 500.

The second intermediate-voltage path MM2 is connected to the firstintermediate-voltage path MM1 via the second inter-system switch 142.The first intermediate-voltage intra-system switch 251 is provided inthe first intermediate-voltage path MM1. The part of the firstintermediate-voltage path MM1 that is on the opposite side of the firstintermediate-voltage intra-system switch 251 from the secondinter-system switch 142 is connected via the first intermediate-voltagecurrent detector 421 to the positive electrode of theintermediate-voltage storage battery 91, and is connected to the firstconnection portion 51A. The negative electrode of theintermediate-voltage storage battery 91 is connected to ground. Powercan be exchanged between the first intermediate-voltage system EM1 andthe first system ES1 via the DC-DC converter 51. The positive electrodeof the first intermediate-voltage load 61 is connected via the firstintermediate-voltage individual switch 351 to the firstintermediate-voltage path MM1 between the second inter-system switch 142and the first intermediate-voltage intra-system switch 251.

The second intermediate-voltage intra-system switch 252 is provided inthe second intermediate-voltage path MM2.

The output side of the intermediate-voltage rotary electrical machine 63is connected via the second intermediate-voltage current detector 422 tothe second intermediate-voltage path MM2, on the opposite side of thesecond intermediate-voltage intra-system switch 252 from the secondinter-system switch 142.

The positive electrode of the second intermediate-voltage load 62 isconnected via the second intermediate-voltage individual switch 352 tothe second intermediate-voltage path MM2 between the second inter-systemswitch 142 and the second intermediate-voltage intra-system switch 252.

The main points of difference of the abnormal operation processing ofthe present embodiment from that of the first embodiment will bedescribed in the following. Output currents that are detected by thecurrent detectors 401, 402, 421, and 422 are used in steps S10, S12, andS15 of FIG. 3,

With this embodiment, even if a ground fault occurs in the firstintermediate-voltage system EM1 or in the second intermediate-voltagesystem EM2, for example, the system in which the ground fault hasoccurred can be disconnected from the other systems.

Modification Example of the Tenth Embodiment

As shown in FIG. 23, a high voltage storage battery 800 may be connectedvia a second DC-DC converter 52, provided as a power output section, tothe second intermediate-voltage path MM2 on the opposite side of thesecond intermediate-voltage intra-system switch 252 from the secondinter-system switch 142. The second DC-DC converter 51 has a voltagestep-down function of stepping down the DC voltage that is outputtedfrom the high voltage storage battery 800, and supplying thestepped-down DC voltage to the second intermediate-voltage system EM2,and a voltage boost function of boosting the DC voltage outputted fromthe intermediate-voltage storage battery 91 and supplying the boosted DCvoltage to the high voltage storage battery 800. With this embodiment,electric power can be supplied from the high voltage storage battery 800to the second intermediate-voltage system EM2 via the second DC-DCconverter 52.

It should be noted that in FIG. 23, with respect to the relationshipbetween the second storage battery 42 and the intermediate-voltagestorage battery 91, the intermediate-voltage storage battery 91corresponds to a high-voltage side storage device, and the secondstorage battery 42 corresponds to a low-voltage side electrical device.Moreover, with respect to the relationship between theintermediate-voltage storage battery 91 and the high voltage storagebattery 800, the high voltage storage battery 800 corresponds to ahigh-voltage side storage device, and the intermediate-voltage storagebattery 91 corresponds to a low-voltage side storage device.

Eleventh Embodiment

An eleventh embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the ninthembodiment. With the present embodiment, the configuration of a powersupply system is changed as shown in FIG. 24. In FIG. 24, componentswhich are identical to components shown in FIG. 21, etc., are designatedby the same reference numerals as in FIG. 21, etc., for convenience.

The power supply system includes a first high voltage storage battery801, a first rotary electrical machine 901, a second high voltagestorage battery 802, and a second rotary electrical machine 902. Thehigh voltage storage batteries 801 and 802 have the same rated voltage,and have a higher rated voltage (for example, several hundred volts)than the first and second storage batteries 41 and 42. Each of the highvoltage storage batteries 801 and 802 is, for example, a lithium-ionstorage battery. A first rotary electrical machine 901 is connected tothe first high voltage storage battery 801. The first rotary electricalmachine 901 is driven by being supplied with power from the first highvoltage storage battery 801. A second rotary electrical machine 902 isconnected to the second high voltage storage battery 802. The secondrotary electrical machine 902 is driven by being supplied with powerfrom the second high voltage storage battery 802. The power system thatis provided with the first high voltage storage battery 801 constitutesa first high-voltage system, and the power system that is provided withthe second high voltage storage battery 802 constitutes a secondhigh-voltage system.

The power supply system includes a first inter-system switch 151 and asecond inter-system switch 152. A second path ML2 is connected to thefirst path ML1 via a first inter-system switch 151. The positiveelectrode of the second high voltage storage battery 802 is connected tothe positive electrode of the first high voltage storage battery 801 viathe second inter-system switch 152. The first inter-system switch 151and the second inter-system switch 152 are operated by the controller500.

The first system ES1 includes first A and B intra-system switches 201Aand 201B, first A and B individual switches 301A and 301B, a firstredundant load 31, and a first normal load 21. The first system ES1includes a first storage battery 41, a first DC-DC converter 71, andfirst A and B current detectors 401A and 401B. The first DC-DC converter71 has a voltage step-down function for stepping down the DC voltagethat is outputted from the first high voltage storage battery 801 andoutputting the stepped-down voltage to the first system ES1, and has avoltage boosting function for boosting the DC voltage that is outputtedfrom the first storage battery 41 and outputting the boosted voltage tothe first high voltage storage battery 801. The first A current detector401A detects the output current of the first DC-DC converter 71 duringthe step-down operation, and outputs the detected current value to thecontroller 500. The first B current detector 401B detects the outputcurrent of the first storage battery 41 and outputs the detected currentvalue to the controller 500.

The second system ES2 includes second A and second B intra-systemswitches 202A and 202B, second A and second B individual switches 302Aand 302B, a second redundant load 32, and a second normal load 22. Thesecond system ES2 includes a second storage battery 42, a second DC-DCconverter 72, and second A and B current detectors 402A and 402B. Thesecond DC-DC converter 72 has a voltage step-down function for steppingdown the DC voltage that is outputted from the second high voltagestorage battery 802 and outputting the stepped-down voltage to thesecond system ES2, and has a voltage boosting function for boosting theDC voltage that is outputted from the second storage battery 42 andoutputting the boosted voltage to the second high voltage storagebattery 802. The second A current detector 402A detects the outputcurrent of the second DC-DC converter 72 during the step-down operation,and outputs the detected current value to the controller 500. The secondB current detector 402B detects the output current of the second storagebattery 42 and outputs the detected current value to the controller 500.

With the present embodiment, the first system ES1 and the firsthigh-voltage system are connected by the first DC-DC converter 71, andthe second system ES1 and the second high-voltage system are connectedby the second DC-DC converter 72. As a result, the first system ES1, thefirst high voltage system, the second high voltage system and the secondsystem ES2 form a ring configuration. It is thereby made possible toreadily specify the location where a ground fault is occurring.

It should be noted that intra-system switches may be provided in thefirst and second high-voltage systems. Specifically, for example, anintra-system switch may be provided in the electrical path that connectsthe positive electrode of the first high voltage storage battery 801 tothe first connection section of the first DC-DC converters 71, and inthe electrical path that connects the positive electrode of the secondhigh voltage storage battery 802 to the first connection section of thesecond DC-DC converter 72.

Modification Example of the Eleventh Embodiment

The manner of installing the intra-system switches in the first systemES1 may be changed as shown in FIG. 25. FIG. 25 illustrates intra-systemswitches 201A, 201B, 201C which are in the first system ES1.Furthermore, the manner of installing the intra-system switches in thesecond system ES2.may be changed as shown in FIG. 25. FIG. 25illustrates intra-system switches 202A, 202B, 202C which are in thesecond system ES2.

Twelfth Embodiment

A twelfth embodiment will be described in the following referring to thedrawings, with a focus on points of difference from the eleventhembodiment. With the present embodiment, the configuration of a powersupply system is changed as shown in FIG. 26. In FIG. 26, componentswhich are identical to components shown in FIG. 24, etc., are designatedby the same reference numerals as in FIG. 24, etc., for convenience.

The power supply system includes first to fourth paths ML1 to ML4 andfirst to fourth inter-system switches 151 to 154. The third path ML3 isconnected to the second path ML2 via the third inter-system switch 153.The fourth path ML4 is connected to the third path ML3 via the fourthinter-system switch 154.

The second system ES2 includes second A and B intra-system switches 232Aand 232B, a second individual switch 302, a second redundant load 32, asecond storage battery 42, a second current detector 402, and a firstalternator 601. The first alternator 601 generates electric power bybeing supplied with power from the output shaft of the engine 700, andoutputs a current. A second current detector 402 is provided in thesecond path ML2. The positive electrode of the second storage battery 42is connected to the second path ML2, and the second current detector 402is disposed between the first inter-system switch 151 and the secondstorage battery 42. Furthermore, the output side of the first alternator601 is connected to the second path ML2 via the second A intra-systemswitch 232A, on the opposite side from the first inter-system switch 151with respect to the second current detector 402.

The third system ES3 includes third A and B inter-system switches 233Aand 233B, a third individual switch 303, a third redundant load 33, athird storage battery 43, a third current detector 403, and a secondalternator 602. The third storage battery 43 has the same rated voltageas the second storage battery 42. The second alternator 602 generateselectric power by being supplied with when power from the output shaftof the engine 700, and outputs a current. A third current detector 403is provided in the third path ML3. The positive electrode of the thirdstorage battery 43 is connected to the third path ML3 between the thirdinter-system switch 153 and third current detector 403. Furthermore, theoutput side of the second alternator 602 is connected to the third pathML3 via the third A intra-system switch 233A between the thirdinter-system switch 153 and the third current detector 403.

The fourth system ES4 includes a fourth intra-system switch 204, fourthA and B individual switches 304A and 304B, a second normal load 22, afourth redundant load 34, a fourth current detector 404, and a secondDC-DC converter 72. The second DC-DC converter 72 has a voltagestep-down function for stepping down the DC voltage that is outputtedfrom the second high voltage storage battery 802 and outputting thestepped-down voltage to the fourth system ES4, and has a voltageboosting function for boosting the DC voltage that is outputted from thefourth system ES4 side and outputting the boosted voltage to the secondhigh voltage storage battery 802. The fourth current detector 404detects the output current of the second DC-DC converter 72 during thestep-down operation.

With this embodiment, the output currents detected by each of thecurrent detectors 401 to 404 may be used in steps S10, S12, and S15 ofFIG. 3, for example.

It should be noted that it would be equally possible for the secondsystem ES2 and the third system ES3 to be provided with normal loads.

Thirteenth Embodiment

A thirteenth embodiment will be described in the following referring tothe drawings with a focus on points of difference from the twelfthembodiment. With this embodiment, the configuration of a power supplysystem is changed as shown in FIG. 27. In FIG. 27, components which areidentical to components shown in FIG. 26 are designated by the samereference numerals as in FIG. 26, for convenience. Illustration of theengine 700 is omitted from FIG. 27.

The first system ES1 includes a first DC-DC converter 81. The firstDC-DC converter 81 has a voltage step-down function for stepping downthe DC voltage that is outputted from the first intermediate-voltagesystem EM1 side and outputting the DC voltage to the first system ES1,and has a voltage boosting function for boosting the DC voltage that isoutputted from the first system ES1 and outputting the voltage to thefirst intermediate-voltage system EM1 side. The first current detector401 detects the output current of the first DC-DC converter 81 duringthe step-down operation.

The fourth system ES4 includes a second DC-DC converter 82. The secondDC-DC converter 82 has a voltage step-down function for stepping downthe DC voltage that is outputted from the third intermediate-voltagesystem EM3 side and outputting the DC voltage to the fourth system ES4side, and has a voltage boosting function for boosting the DC voltagethat is outputted from the fourth system ES4 and outputting the voltageto the third intermediate-voltage system EM3 side. The fourth currentdetector 404 detects the output current of the second DC-DC converter 82during the step-down operation.

The power supply system includes first to fourth intermediate-voltagesystems EM1 to EM4, fifth to seventh inter-system switches 155 to 157,and first to fourth intermediate-voltage paths MM1 to MM4.

The first intermediate-voltage system EM1 includes first A and Bintermediate-voltage intra-system switches 251A and 251B, a firstintermediate-voltage individual switch 351, a first intermediate-voltagestorage battery 91, a first intermediate-voltage alternator 611, and afirst intermediate-voltage current detector 421. The firstintermediate-voltage storage battery 91 has a rated voltage which islower than that of the high voltage storage batteries 801 and 802 and ishigher than that of the second and third storage batteries 42 and 43.The first intermediate-voltage alternator 611 generates electric powerfrom power that is supplied from the output shaft of engine 700, andoutputs a current. The first intermediate-voltage alternator 611 has ahigher rated output voltage than that of the first and secondalternators 601 and 602.

The first intermediate-voltage path MM1 is provided with first A and Bintermediate-voltage intra-system switches 251A and 251B. The secondintermediate-voltage path MM2 is connected via the fifth inter-systemswitch 155 to one side of the first intermediate-voltage path MM1, andthe first connection section of the first DC-DC converter 81 isconnected to the other side of the first intermediate-voltage path MM1.The positive electrode of the first intermediate-voltage load 61 isconnected via the first intermediate-voltage individual switch 351 tothe second intermediate-voltage path MM2 between the fifth inter-systemswitch 155 and the first B intermediate-voltage intra-system switch251B. In the second intermediate-voltage path MM2, the positiveelectrode of the first intermediate-voltage storage battery 91 isconnected between the first A intermediate-voltage intra-system switch251A and the first B intermediate-voltage intra-system switch 251B. Theoutput side of the first intermediate-voltage alternator 611 isconnected to the second intermediate-voltage path MM1 between the firstDC-DC converter 81 and the first A intermediate-voltage intra-systemswitch 251A. A first intermediate-voltage current detector 421 isprovided in the second intermediate-voltage path MM2, on the first Bintermediate-voltage intra-system switch 251B side, on the opposite sidefrom the connection point with the first intermediate-voltage storagebattery 91.

The second intermediate-voltage system EM2 includes a secondintermediate-voltage intra-system switch 252, a secondintermediate-voltage individual switch 352, a secondintermediate-voltage load 62, a third DC-DC converter 83, and a secondintermediate-voltage current detector 422. A second intermediate-voltageintra-system switch 252 is provided in the second intermediate-voltagepath MM2. The positive electrode of the second intermediate-voltage load62 is connected via the second intermediate-voltage individual switch352 to the second intermediate-voltage path MM2 between the fifthinter-system switch 155 and the second intermediate-voltage intra-systemswitch 252. The second connection section of the third DC-DC converter83 is connected via the second intermediate-voltage path MM2 to thesecond intermediate-voltage intra-system switch 252, on the sideopposite the fifth inter-system switch 155. The third DC-DC converter 83has a voltage step-down function for stepping down the DC voltage thatis outputted from the first high voltage storage battery 801 andoutputting the DC voltage to the second intermediate-voltage system EM2side, and has a voltage boosting function for boosting the DC voltagethat is outputted from the second intermediate-voltage system EM2 andoutputting the voltage to the first high voltage storage battery 801.The second intermediate-voltage current detector 422 detects the outputcurrent of the third DC-DC converter 83 during the step-down operation.

The third path MM3 is connected via the sixth inter-system switch 156 tothe first DC-DC converter 81 side of the first intermediate-voltage pathMM1

The third intermediate-voltage system EM3 includes third A and Bintermediate-voltage intra-system switches 253A and 253B a thirdintermediate-voltage individual switch 353, a secondintermediate-voltage storage battery 92, a second intermediate-voltagealternator 612, and a third intermediate-voltage current detector 423.The second intermediate-voltage storage battery 92 has the same ratedvoltage as the first intermediate-voltage storage battery 91. The secondintermediate-voltage alternator 612 generates electric power from powerthat is supplied from the output shaft of engine 700, and outputs acurrent. The second intermediate-voltage alternator 612 has the samerated output voltage as the first intermediate-voltage alternator 611.

Third A and B intermediate-voltage intra-system switches 253A and 253Bare provided in the third intermediate-voltage path MM3. A fourthintermediate-voltage path MM4 is connected to the thirdintermediate-voltage path MM3, on the side opposite the connection pointwith the sixth inter-system switch 156, via a seventh inter-systemswitch 157. The positive electrode of the third intermediate-voltageload 63 is connected to the third intermediate-voltage path MM3 betweenthe seventh inter-system switch 157 and the third B intermediate-voltageintra-system switch 253B, via the third intermediate-voltage individualswitch 353. In the third intermediate-voltage path MM3, the positiveelectrode of the second intermediate-voltage storage battery 92 isconnected between the third A intermediate-voltage intra-system switch253A and the third B intermediate-voltage intra-system switch 253B. Thepositive electrode of the second intermediate-voltage storage battery 92is connected to the third intermediate-voltage path MM3 on the side ofthe connection point the third A intermediate-voltage intra-systemswitch 253A and the sixth intersystem switch 156. The output side of thesecond intermediate-voltage alternator 612 is connected to the thirdintermediate-voltage path MM3 between the second DC-DC converter 82 andthe third A intermediate-voltage intra-system switch 253A. A thirdintermediate-voltage current detector 423 is provided in the thirdintermediate-voltage path MM3, on the side of the connection pointbetween the third B intermediate-voltage intra-system switch 253B andthe second intermediate-voltage storage battery 92.

The fourth intermediate-voltage system EM4 includes a fourthintermediate-voltage intra-system switch 254, a fourthintermediate-voltage individual switch 354, a fourthintermediate-voltage load 64, a fourth DC-DC converter 84, and a fourthintermediate-voltage current detector 424. The fourthintermediate-voltage intra-system switch 254 is provided in the fourthintermediate-voltage path MM4. The positive electrode of the fourthintermediate-voltage load 64 is connected via the fourthintermediate-voltage individual switch 354 to the seventh inter-systemswitch 157 between the fourth intermediate-voltage path MM4 and thefourth intermediate-voltage intra-system switch 254. The secondconnection section of the fourth DC-DC converter 84 is connected in thefourth intermediate-voltage path MM4, on the side that is opposite theseventh inter-system switch 157, with respect to the fourthintermediate-voltage intra-system switch 254. The fourth DC-DC converter84 has a voltage step-down function for stepping down the DC voltagethat is outputted from the second high voltage storage battery 802 andsupplying the voltage to the fourth intermediate-voltage system EM4side, and has a voltage boosting function for boosting the DC voltage ofthe fourth intermediate-voltage system EM4 and supplying the voltage tothe second high voltage storage battery 802. The fourthintermediate-voltage current detector 424 detects the output current ofthe fourth DC-DC converter 84 during the step-down operation.

With present embodiment, it would be equally possible to use the outputcurrents that are detected by the current detectors 401 to 404 and 421to 424 in steps S10, S12, and S15 of FIG. 3, for example.

It should be noted that at least two of the intermediate-voltage systemsEM1 to EM4 may be provided with redundant loads.

Modification Example of Thirteenth Embodiment

As shown in FIG. 28, the third DC-DC converter 83 and the fourth DC-DCconverter 84 may be made capable of exchanging electric power with thecommon high voltage storage battery 800.

Fourteenth Embodiment

A fourteenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the twelfthembodiment. With this embodiment, the configuration of a power supplysystem is changed as shown in FIG. 29. In FIG. 29, components which areidentical to components shown in FIGS. 26, 27, etc., are designated bythe same reference numerals as in FIGS. 26, 27, etc., for convenience.

The second system ES2 and the second intermediate-voltage system EM2 canexchange power via the first DC-DC converter 81. The third system ES3and the fourth intermediate-voltage system EM4 can exchange power viathe second DC-DC converter 82.

The same effects as those of the twelfth embodiment can be obtained withthe present embodiment described above.

Fifteenth Embodiment

A fifteenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the firstembodiment. With this embodiment, the configuration of the inter-systemswitches and the intra-system switches is changed, as shown in FIG. 30.In FIG. 30, components which are identical to components shown in FIG.1, etc., are designated by the same reference numerals as in FIG. 1,etc., for convenience

A power supply system includes a first module MJ1 and a second moduleMJ2. The first module MJ1 includes first A to C switches 261 a to 261 cand a first intermediate switch 160 a. Each of the switches 261 a to 261c and 160 a is an N-channel MOS FET. The drain of the first A switch 261a is connected to the drain of the first B switch 261 b. The source ofthe first B switch 261 b is connected to the drain of the first C switch261 c and to the source of the first intermediate switch 160 a. Thepositive electrodes of the first redundant load 31 and the normal load21 are connected to the source of the first C switch 261 c. The first Aswitch 261 a and the first B switch 261 b are provided in the first pathML1.

The second module MJ2 includes second A to second C switches 262 a to262 c and a second intermediate switch 160 b. Each of the switches 262 ato 262 c and 160 b is an N-channel MOS FET. The drain of the second Bswitch 262 b is connected to the drain of the second A switch 262 a. Thesource of the second B switch 262 b is connected to the drain of thesecond C switch 262 c and the source of the second intermediate switch160 b. The positive electrode of the second redundant load 32 isconnected to the source of the second C switch 262 c. The drain of thefirst intermediate switch 160 a is connected to the drain of the secondintermediate switch 160 b. The second A switch 262 a and the second Bswitch 262 b are provided in the second path ML2. With the presentembodiment, the configurations of the first and second modules MJ1 andMJ2 are identical.

With the present embodiment, the first intermediate switch 160 a and thesecond intermediate switch 160 b constitute an inter-system switch 160.Furthermore, the first A to first C switches 261 a to 261 c constitute afirst module switch 261, and the first module switch 261 constitutes anintra-system switch and an individual switch of the first system ES1.Furthermore, the second A to second C switches 262 a to 262 c constitutea second module switch 272, and the second module switch 272 constitutesan intra-system switch and an individual switch of the second systemES2.

The first and second intermediate switches 160 a and 160 b constitutingthe inter-system switch 160 are operated in the same manner as theinter-system switch 100 in FIG. 1. Since the drains of the first andsecond intermediate switches 160 a and 160 b are connected to oneanother, bidirectional current flow is prevented when a switch is turnedoff.

The first A and B switches 261 a and 261 b are operated in the samemanner as the first intra-system switch 201 in Fig. Since the drains ofthe first A and B switches 261 a and 261 b are connected to one another,bidirectional current flow is prevented when a switch is turned off. Thefirst C switch 261 c is operated in the same manner as the first Aindividual switch 301A or the first B individual switch 301B in FIG. 1.

The second A and B switches 262 a and 262 b are operated in the samemanner as the second intra-system switch 202 in FIG. 1. The second Cswitch 262 c is operated in the same manner as the second individualswitch 302 in FIG. 1.

According to the first A switch 261 a, even if a ground fault occurs inthe first power output section 11, overcurrent flow can be prevented byturning off the first A switch 261 a. Furthermore, according to thesecond A switch 262 a, even if a ground fault occurs in the second poweroutput section 12, overcurrent flow can be prevented by turning off thesecond A switch 262 a.

Sixteenth Embodiment

A sixteenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the fifteenthembodiment. With this embodiment the configuration of the inter-systemswitches and the intra-system switches is changed, as shown in FIG. 31.In FIG. 31, components which are identical to components shown in FIG.8, etc., are designated by the same reference numerals as in FIG. 8,etc., for convenience

A power supply system includes a first module MJA and a second moduleMJB. The first module MJA includes a first A switch 271 a and first Bswitch 271 b, and a first intermediate switch 161 a. Each of theswitches 271 a, 271 b and 161 a is an N-channel MOS FET. The drain ofthe first B switch 271 b is connected to the drain of the first A switch271 a. The source of the first B switch 271 b is connected to the sourceof the first intermediate switch 161 a and to a first A fuse 311A and afirst B fuse 311B. The first A switch 271 a and the first B switch 271 bare provided in the first path ML1.

The second module MJB includes a second A switch 272 a and second Bswitch 272 b, and a second intermediate switch 161 b. Each of theswitches 272 a, 272 b and 161 b is an N-channel MOS FET. The drain ofthe second B switch 272 b is connected to the drain of the second Aswitch 272 a. The source of the second intermediate switch 161 b and thesecond fuse 312 are connected to the source of the second B switch 272b. The drain of the first intermediate switch 161 a is connected to thedrain of the second intermediate switch 161 b. The second A switch 272 aand the second B switch 272 b are provided in the second path ML2. Thefirst and second modules MJA and MJB of the present embodiment have anidentical configuration.

With the present embodiment, the first intermediate switch 161 a and thesecond intermediate switch 161 b constitute an inter-system switch 161.Furthermore, the first A and B switches 271 a and 271 b constitute afirst intra-system switch 271 of the first system ES1. Moreover, thesecond A and B switches 272 a and 272 b constitute a second intra-systemswitch 272 of the second system ES2.

The first and second intermediate switches 161 a and 161 b whichconstitute the inter-system switch 161 are operated in the same manneras the inter-system switch 100 in FIG. 3. The first A and B switches 271a and 271 b are operated in the same manner as the first intra-systemswitch 201 in FIG. 1. The second A and B switches 272 a and 272 b areoperated in the same manner as the second intra-system switch 202 inFIG. 1.

Seventeenth Embodiment

A seventeenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the sixteenthembodiment. With this embodiment, the configuration of the inter-systemswitches and the intra-system switches is changed, as shown in FIG. 32.In FIG. 32, components which are identical to components shown in FIG.31, etc., are designated by the same reference numerals as in FIG. 31,etc., for convenience.

A power supply system includes a first module MJα and a second moduleMJβ. The first module MJα includes first A to first D switches 281 a to281 d, a first intermediate switch 162 a and a second intermediateswitch 162 b. Each of the switches 281 a to 281 d, 162 a, 162 b is anN-channel MOS FET. The drains of the first A switch 281 a and the firstB switch 281 b are connected to one another, and the drains of the firstC switch 281 c and the first D switch 281 d are connected to oneanother. The source of the first C switch 281 c is connected to thesource of the first B switch 281 b. The source of the first intermediateswitch 162 a and a first A fuse 311A and first B fuse 311B are connectedto the source of the first D switch 281 d. The first A to first Dswitches 281 a to 281 d are provided in the first path ML1.

The second module MJβ includes second A to second D switches 282 a to282 d, a third intermediate switch 162 c, and a fourth intermediateswitch 162 d. Each of the switches 282 a-282 d, 162 c and 162 d is anN-channel MOS FET. The drains of the second A switch 282 a and thesecond B switch 282 b are connected to one another, and the drains ofthe second C switch 282 c and the second D switch 282 d are connected toone another. The source of the second C switch 282 c is connected to thesource of the second B switch 282 b. The source of the secondintermediate switch 162 c and a second fuse 312 are connected to thesource of the second D switch 282 d. The second A to second D switches282 a to 282 d are provided in the second path ML2. With the presentembodiment, the first and second modules MJα and MJβ have an identicalconfiguration.

The drains of the first intermediate switch 162 a and the secondintermediate switch 162 b are connected to one another, and the drainsof the third intermediate switch 162 c and the fourth intermediateswitch 162 d are connected to one another. The source of the fourthintermediate switch 162 d is connected to the source of the secondintermediate switch 162 b.

With the present embodiment, the first to fourth intermediate switches162 a to 162 d constitute the inter-system switch 162. The first A tofirst D switches 281 a to 281 d constitute the first intra-system switch281 of the first system ES1. The second A to second D switches 282 a to282 d constitute the second intra-system switch 282 of the second systemES2.

The first to fourth intermediate switches 162 a to 162 d whichconstitute the inter-system switch 162 are operated in the same manneras the inter-system switch 100 in FIG. 1. The first to first D switches281 a to 281 d are operated in the same manner as the first intra-systemswitch 201 of FIG. 1. The second A to second D switches 282 a to 282 dare operated in the same manner as the second intra-system switch 202 inFIG. 1.

With the present embodiment described above, each of the switches 162,281, and 282 includes two sets of N-channel MOS FETs, with the drains ofthe MOS FETs connected to one another. As a result, even if ashort-circuit occurs in any of the N-channel MOS FETs constituting aswitch, the function of preventing bidirectional current flow ismaintained when the switch is turned off.

It should be noted that it would be equally possible to for each of themodules MJα and MJβ to include three sets of N-channel MOS FETs, withthe sources of the MOS FETs connected to one another, instead of theN-channel MOS FETs with drains connected to one another.

Eighteenth Embodiment

An eighteenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the seventeenthembodiment. With this embodiment, the configuration of the inter-systemswitches and the intra-system switches is changed, as shown in FIG. 33.In FIG. 33, components which are identical to components shown in FIG.32, etc., are designated by the same reference numerals as in FIG. 32,etc., for convenience.

A power supply system includes a first module 291, a second module 292,and an intermediate module 163. The first module 291 corresponds to anintra-system switch of the first system ES1, the second module 292corresponds to an intra-system switch of the second system ES2, and theintermediate module 163 corresponds to an inter-system switch. With thepresent embodiment, the modules 291, 292, and 163 have an identicalconfiguration.

The first module 291 includes first A to first D switches 291 a to 291d. Each of the switches 291 a to 291 d is an N-channel MOS FET. Thedrains of the first A switch 291 a and the first B switch 291 b areconnected to one another, and the drains of the first C switch 291 c andthe first D switch 291 d are connected to one another. The seriesconnection body formed of the first C switch 291 c and the first Dswitch 291 d is connected in parallel with the series connection bodyformed of the first A switch 291 a and the first B switch 291 b. Thefirst A fuse 311A and the first B fuse 311B are connected to the sourcesof the first B and first D switches 291 b and 291 d. The first A tofirst D switches 291 a to 291 d are provided in the first path ML1.

The second module 292 includes second A to second D switches 292 a to292 d. Each of the switches 292 a to 292 d is an N-channel MOS FET. Thesecond A to second D switches 292 a to 292 d are provided in the secondpath ML2. The intermediate module 163 includes first to fourthintermediate switches 163 a to 163 d. Each of the switches 163 a to 163d is an N-channel MOS FET. The sources of the second A and C switches292 a and 292 c are connected to the sources of the second and fourthintermediate switches 163 b and 163 d. The sources of the first B andfirst D switches 291 b and 291 d are connected to the sources of thefirst and third intermediate switches 163 a and 163 c.

With the present embodiment, each of the modules 291, 292, and 163 isconfigured as a parallel connection of bodies that are each formed ofN-channel MOS FETs whose drains are connected to one another. Thisconfiguration is provided in view of the case in which either of theN-channel MOS FETs constituting a switch becomes short-circuited. Thatis, even when a MOS FET is short-circuited, the short-circuited MOS FETwill have a resistance value that is greater than the on-stateresistance value of a MOS FET that has been turned on. Hence, since eachmodule is configured as a parallel connection of a pair of bodies formedof series-connected MOS FETs, even if a short circuit failure occurs inone of the series-connected MOS FET bodies of a module, a high level ofcurrent can flow through the series-connected MOS FET body in which ashort-circuit failure has not occurred. As a result, the generation ofheat by MOS FETs in which a short circuit failure has occurred can besuppressed.

It should be noted that each of the modules 163, 291 and 292 may includetwo sets of N-channel MOS FETs whose sources are connected, instead ofthe N-channel MOS FETs whose drains are connected. Furthermore, in eachof the modules 163, 291 and 292, three or more series-connected MOS FETbodies may be connected in parallel.

Nineteenth Embodiment

A nineteenth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the eighteenthembodiment. With this embodiment, the configuration of the inter-systemswitches and the intra-system switches is changed, as shown in FIG. 34.In FIG. 34, components which are identical to components shown in FIG.33, etc., are designated by the same reference numerals as in FIG. 33,etc., for convenience.

A power supply system includes first to third modules M1 to M3. Thefirst module M1 corresponds to an intra-system switch of the firstsystem ES1, the second module M2 corresponds to an intra-system switchof the second system ES2, and the third module M3 corresponds to aninter-system switch. With the present embodiment, the modules M1 to M3have an identical configuration.

The first module M1 includes four first element groups 293. The firstmodule M1 is configured by connecting series connection bodies, eachformed of two first element groups 293, in parallel with one another.The second module M2 includes four second element groups 294, and thethird module M3 includes four third element groups 295.

With the present embodiment, each of the element groups 293 to 295 has aconfiguration in which, as for the modules 291, 292, and 163 shown inFIG. 33, two N-channel MOS FET series connection bodies are connected inparallel. As a result, each of the first to third modules M1 to M3includes 16 MOS FETs. The same effects as those of the seventeenth andeighteenth embodiments can be obtained with this embodiment.

Twentieth Embodiment

A twentieth embodiment will be described in the following referring tothe drawings, with a focus on points of difference from the firstembodiment. With the present embodiment, as shown in FIG. 35, the firstA individual switch 301A, the first B individual switch 301B, and thesecond individual switch 302 of the configuration shown in FIG. 1 areomitted. As a result, the first redundant load 31 and the normal load 21are connected to the first path ML1 without using individual switches,and the second redundant load 32 is connected to the second path ML2without using an individual switch. In FIG. 35, components which areidentical to components shown in FIG. 1 are designated by the samereference numerals as in FIG. 1, for convenience.

A power supply system does not include the first current detector 401 orthe second current detector 402. With the present embodiment, theinter-system switch 100, the first intra-system switch 201, and thesecond intra-system switch 202 constitute a current detector. As aresult, it becomes unnecessary to provide a current sensor or a shuntresistor, etc. The inter-system switch 100 will be described as anexample. As shown in FIG. 36, the inter-system switch 100 consists oftwo N-channel MOS FETs whose sources are connected together. The voltageVds between the terminals of the inter-system switch 100 is detected bythe controller 500. The controller 500 detects the magnitude anddirection of the current flowing through the inter-system switch 100based on the detected inter-terminal voltage Vds.

FIG. 37 describes operation processing that is executed when anabnormality occurs with the present embodiment. This processing isexecuted by the controller 500.

In step S50, the flow direction and magnitude of the respective currentsflowing through each of the inter-system switch 100, the firstintra-system switch 201 and the second intra-system switch 202 aredetected, by the detection method described above. With the presentembodiment, the processing of step S50 corresponds to a directiondetection section.

In step S51, a switch that is to be turned off is specified, from amongthe inter-system switch 100, the first intra-system switch 201 and thesecond intra-system switch 202, based on the detected directions ofcurrent flow through the inter-system switch 100, the first intra-systemswitch 201 and the second intra-system switch 202. The processing ofstep S51 corresponds to a switch group specifying section and a targetswitch specifying section. This specifying method will be described inthe following referring to FIGS. 38 and 39.

A to H shown in FIG. 38 are examples of ground fault occurrencelocations. A is the first power output section 11, B is a part of thefirst path ML1 that is between the first intra-system switch 201 and thefirst power output section 11, and C is a part of the first path ML1that is between the first intra-system switch 201 and the inter-systemswitch 100. D is a part of the second path ML2 that is the between theinter-system switch 100 and the second intra-system switch 202, and E isa part of the second path ML2 that is the between the secondintra-system switch 202 and the second power output section. 12, and Fis the second power output section 12. G is an electrical path thatconnects the first path ML1 to the positive electrodes of the normalload 21 and the first redundant load 31, and connects the normal load 21to the first redundant load 31. H is an electrical path that connectsthe second path ML2 to the positive electrode of the redundant load 32,or the redundant load 32.

FIG. 39 shows the relationship between the location where a ground faultoccurs, the directions and magnitudes of current flow through theinter-system switch 100, the first intra-system switch 201 and thesecond intra-system switch 202, and the switch that is specified to beturned off in step S51.

If no ground fault has occurred in the power supply system, as shown inrow (a) of FIG. 39, none of the inter-system switch 100, the firstintra-system switch 201 or the second intra-system switch 202 isspecified to be turned off. In row of (a) of FIG. 39, as an example, thedirections of current flow through all of the inter-system switch 100,the first intra-system switch 201, and the second intra-system switch202 are from the first power output section 11 to the second poweroutput section 12.

When the ground fault occurrence location is A or B, then as shown inthe row (b) of FIG. 39, it is judged that all of the current flowdirections of the inter-system switch 100, the first intra-system switch201 and the second intra-system switch 202 are identical. In that case,among the inter-system switch 100, the first intra-system switch 201,and the second intra-system switch 202, the first intra-system switch201 (corresponding to the target switch), which is the switch that isthe most downstream with respect to the current flow direction, isspecified to be turned off.

When the ground fault occurrence location is C or G as shown in row (c)of FIG. 39, the first intra-system switch 201 and the inter-systemswitch 100 (corresponding to a switch group), which are a group of theswitches that are adjacent to one another among the inter-system switch100, the first intra-system switch 201 and the second intra-systemswitch 202, and whose detected current flow directions are opposite toone another, are specified as the targets for turn-off operation.

When a ground fault occurs, a high level of current flows from the poweroutput sections 11 and 12 toward the ground fault occurrence location.Hence, among the inter-system switch 100 and the intra-system switches201 and 202, the directions of current flow through the switches in thegroup that are disposed in the first and second paths ML1 and ML2,adjacent to the ground fault occurrence location, become opposite to oneanother. As a result, it is possible to specify the ground faultoccurrence location, by specifying such a switch group.

When the ground fault occurrence location is D or H, as shown in row (d)of FIG. 39, then the inter-system switch 100 and the second intra-systemswitch 202 (corresponding to a switch group) are specified as theturn-off operation targets, these being the switches which are adjacentamong the inter-system switch 100, the first intra-system switch 201 andthe second intra-system switch 202, and whose directions of current floware opposite to one another.

When the ground fault occurrence location is E or F, then as shown inrow (e) of FIG. 39, it is judged that the directions of current flow inthe inter-system switch 100, the first intra-system switch 201 and thesecond intra-system switch 202 are each identical. In that case, thesecond intra-system switch 202 (corresponding to the target switch) isspecified as the turn-off operation target, that switch being the onewhich is the most downstream, with respect to the current flowdirection, among the inter-system switch 100, the first intra-systemswitch 201 and the second intra-system switch 202.

The switch specified in step S51 is registered in a storage device suchas a memory, provided in the controller 500.

Returning to the description of FIG. 37, in step S52, if a plurality ofswitches are specified in step S51, then a decision is made as towhether the current flowing in at least one of these switches exceeds athreshold value of current Iα. With the present embodiment, a decisionis made as to whether the current flowing through all of the pluralityof switches specified in step S51 exceeds the threshold value of currentIα. The processing of step S52 serves to judge whether a ground faulthas occurred. The threshold value of current Iα is set, for example, asthe maximum value that can be attained for the output current if noground fault has occurred in the power supply system.

Furthermore, if a single switch is specified in step S51, then adecision is made in step S52 as to whether the level of current flowingthrough that switch exceeds the threshold value of current Iα.

If a negative decision is made in step S52, the inter-system switch 100,the first intra-system switch 201, and the second intra-system switch202 are maintained turned on.

On the other hand, if an affirmative decision is made in step S52, theprocessing proceeds to step S53, and the switch specified in step S53 isturned off. The processing of step S53 corresponds to a changeoveroperation section. A specific example of the processing of step S53 willbe described in the following.

When the ground fault occurrence location is A or B, the firstintra-system switch 201 is turned off. In that way, the first electricpower output section 11, and the part of the first path ML1 between thefirst electric power output section 11 and the first intra-system switch201 can be disconnected from the power supply system.

When the ground fault occurrence location is C or G, the firstintra-system switch 201 and the inter-system switch 100 are turned off.In that way, the first path ML1, the normal load 21, the first redundantload 31, and the first power output section 11 can be disconnected fromthe power supply system.

When the ground fault occurrence location is D or H, the inter-systemswitch 100 and the second intra-system switch 202 are turned off. Inthat way, the part of the second path ML2 that is between theinter-system switch 100 and the second intra-system switch 202, and thesecond redundant load 32, can be disconnected from the power supplysystem.

When the ground fault occurrence location is E or F, the secondintra-system switch 202 is turned off. In that way, the part of thesecond path ML2 between the second electric power output section 12 andthe second intra-system switch 202, and the second electric power outputsection 12 can be disconnected from the power supply system.

Twenty-First Embodiment

A twenty-first embodiment will be described in the following referringto the drawings, with a focus on points of difference from the twentiethembodiment. With the present embodiment, as shown in FIG. 40, a firstindividual switch 301 and a second individual switch 302 are provided.The first individual switch 301 is disposed in the electrical path thatconnects the respective positive electrodes of the normal load 21 andthe first redundant load 31 to the first path ML1. The first individualswitch 301 and the second individual switch 302 are operated by thecontroller 500. The first individual switch 301 and the secondindividual switch 302 may for example be formed of individual N-channelMOS FETs, as with the switches indicated by reference numerals 261 c and262 c in FIG. 30 above. In FIG. 40, components which are identical tocomponents shown in FIG. 35 above are designated by the same referencenumerals as in FIG. 35, for convenience.

FIG. 41 describes the operation processing executed when an abnormalityoccurs with the present embodiment. This processing is executed by thecontroller 500. In FIG. 41, components which are identical to componentsshown in FIG. 37 above are designated by the same reference numerals asin FIG. 37, for convenience.

In step S51, a switch that is to be turned off is specified, from amongthe inter-system switch 100, the first intra-system switch 201, and thesecond intra-system switch 202, based on the detected directions ofcurrent flow in the inter-system switch 100, the first intra-systemswitch 201, and the second intra-system switch 202. The processing ofstep S51 corresponds to an individual switch specifying section. Thisspecifying method is described in the following referring to FIGS. 42and 43. The ground fault occurrence locations shown in FIG. 42, whichare different from the ground fault occurrence locations shown in FIG.38 above, consist of G, H, C, and D, where: G is a path that is part ofthe electrical paths that connect the positive electrodes of the normalload 21 and the first redundant load 31 to the first path ML1, and isbetween the normal load 21 and the first redundant load 31 and the firstindividual switch 301, or is the normal load 21, or the first redundantload 31; H is a part of the electrical path that connects the secondpath ML2 to the positive electrode of the second redundant load 32 andis between the second redundant load 32 and the second individual switch302, or is the second redundant load 32; C is the part of the first pathML1 that is sandwiched between the first intra-system switch 201 and theinter-system switch 100, or is the part of the electrical path whichconnects the positive electrodes of the normal load 21 and the firstredundant load 31 to the first path ML1 and is between the first pathML1 and the first individual switch 301; and D is the part of the secondpath ML2 that is sandwiched between the inter-system switch 100 and thesecond intra-system switch 202, or is the part of the electrical paththat connects the second path ML2 to the positive electrode of thesecond redundant load 32 and is between the second path ML2 and theindividual switch 302.

When the ground fault occurrence location is C or G, then in addition tothe first intra-system switch 201 and the inter-system switch 100, thefirst individual switch 301 is specified as a target to be turned off,as shown in row (c) of FIG. 43. The first individual switch 301 isconnected to a part of the first and second paths ML1 and ML2 sandwichedbetween the first intra-system switch 201 and the inter-system switch100.

When the ground fault occurrence location is D or H, then as shown inrow (d) of FIG. 43, in addition to the inter-system switch 100 and thesecond intra-system switch 202, the second individual switch 302 isspecified as a turn-off operation target.

Returning to the description of FIG. 41, if an affirmative decision ismade in step S52, the processing proceeds to step S54. In step S54, adecision is made as to whether an individual switch is included in theswitches specified in step S51. If a negative decision is made in stepS54, it is judged that no individual switch is specified as a turn-offoperation target, and the processing proceeds to step S53. In step S53,all of the switches specified in step S51 are turned off.

On the other hand, if it is judged in step S54 that the first individualswitch 301 or the second individual switch 302 has been specified as aturn-off operation target, the processing proceeds to step S55. In stepS55, the individual switch specified in step S51 is turned off.

In step S56, a decision is made as to whether all of the currentsflowing through the inter-system switch 100, the first intra-systemswitch 201, and the second intra-system switch 202 are equal to or lessthan the threshold value of current Iα. If a negative decision is madein step S56, the processing proceeds to step S53.

If an affirmative decision is made in step S56, then of all the switchesspecified in step S51, only the individual switches turned off in stepS55 are maintained in the off state.

With the present embodiment described above, even when a ground faultoccurs in a power supply system, it is made possible to determine thepart of the power supply system which is unusable due to the groundfault, as closely as possible.

Twenty-Second Embodiment

A twenty-second embodiment will be described in the following referringto the drawings, with a focus on points of difference from thetwenty-first embodiment. With the present embodiment as shown in FIG.44, a first current detector 401 and second current detector 402 areprovided, having the configuration shown in FIG. 40 above. In FIG. 44,configuration parts which are identical to parts shown in FIG. 40 andFIG. 1 above are designated by the same reference numerals as in FIG. 40and FIG. 1, for convenience.

FIG. 45 is a diagram for describing operation processing that isexecuted when an abnormality occurs with the present embodiment. Thisprocessing is executed by the controller 500. In FIG. 45, processingsteps which are identical to these shown in FIG. 41 are above aredesignated by the same reference numerals as in FIG. 41, forconvenience.

In step S58, the first output current Ir1 and the second output currentIr2 are detected. Furthermore, in step S58, the respective directions ofcurrent flow in the inter-system switch 100, the first intra-systemswitch 201 and the second intra-system switch 202 are detected. Theinter-system switch 100 will be described as an example. With thepresent embodiment, the current flow direction of the inter-systemswitch 100 is detected based on the magnitude relationship between thevoltages at each of the ends of the inter-system switch 100. Forexample, if the voltage at the end of the inter-system switch 100 thatis on the side of the first path ML1 is higher than the voltage at theend of the inter-system switch 100 which is on the side of the secondpath ML2, then it is judged that the direction of current flow in theinter-system switch 100 has changed to a direction oriented from thefirst path ML1 side toward the second path ML2 side. When the processingof step S58 is completed, the processing proceeds to step S51.

After step S51 is completed, in step S59, a decision is made as towhether at least one of the first output current Ir1 and the secondoutput current Ir2 detected in step S58 exceeds the threshold value ofcurrent Iα. With the present embodiment a decision is made as to whetherboth the first output current Ir1 and the second output current Ir2exceed the threshold value of current Iα.

If a negative decision is made in step S59, the turned-on state of theinter-system switch 100, the first intra-system switch 201, and thesecond intra-system switch 202 is maintained. On the other hand, if anaffirmative decision is made in step S59, the processing proceeds tostep S54.

After step S60 is completed, the processing proceeds to step S60. Instep S60, a decision is made as to whether both the condition that thefirst output current Ir1 is equal to or smaller than the threshold valueof current Iα and also the condition that the second output current Ir2is equal to or smaller than the threshold value of current Iα aresatisfied. If a negative decision is made in step S60, the processingproceeds to step S53.

With the present embodiment described above, the same effects as thoseof the twenty-second embodiment can be obtained.

Twenty-Third Embodiment

A twenty-third embodiment will be described in the following referringto the drawings, with a focus on points of difference from thetwenty-first embodiment. With the present embodiment, the first currentdetector 401 and the second current detector 402 are omitted from theconfiguration shown in FIG. 1 above.

The controller 500 detects the respective magnitudes of current flow anddirections of current flow in the inter-system switch 100, the firstintra-system switch 201, the second intra-system switch 202, the first Aindividual switch 301A, the first B individual switch 301B, and thesecond individual switch 302, based on the detected inter-terminalvoltage Vds.

FIG. 46 shows ground fault occurrence locations for this embodiment. Theground fault occurrence locations shown in FIG. 46 that are differentfrom those in FIG. 42 above are as follows. G is an electrical pathconnecting the first B individual switch 301B and the positive electrodeof the normal load 21, or is the normal load 21. I is an electrical pathconnecting the first A individual switch 301A and the positive electrodeof the first redundant load 31, or is the first redundant load 31. C isa part of the first path ML1 that is sandwiched between the firstintra-system switch 201 and the inter-system switch 100, or is anelectrical path connecting the first A individual switch 301A and thefirst B individual switch 301B to the first path ML1.

The operation processing executed with this embodiment when anabnormality occurs will be described in the following. The controller500 specifies a plurality of individual switches which are connected tothe parts of the first and second paths ML1 and ML2 that are enclosed bythe switch group specified in step S51 of FIG. 41. If the controller 500makes positive decisions in steps S52 and S54 of FIG. 41, then in stepS55, those of the specified plurality of individual switches for whichthe level of current flow exceeds the threshold value of current Iα areturned off, while maintaining the intra-system switches that werespecified in step S51, and the inter-system switch 100, in the turned-onstate.

Specifically, if the controller 500 specified the inter-system switch100 and the first intra-system switch 201 as turn-off operation targetsin step S51, then the first A individual switch 301A and the first Bindividual switch 301B, which are connected to the part of the firstpath ML1 that is sandwiched between the inter-system switch 100 and thefirst intra-system switch 201, are specified. If the controller 500subsequently makes an affirmative decision in steps S52 and S54, then instep S55 the controller 500 turns off the one of the first A individualswitch 301A and first B individual switch 301B for which the currentflow exceeds the threshold value of current Iα. This processing servesto accurately specify the location where a ground fault occurs. Themethod of specifying will be described in the following referring toFIG. 47. In FIG. 47, “HIGH” indicates that the level of current flowexceeds the threshold value of current Iα, and “LOW” indicates that thelevel of current flow is equal to or less than the threshold value ofcurrent Iα.

When the ground fault occurrence location is C, G, or I, theinter-system switch 100 and the first intra-system switch 201 arespecified as the turn-off operation targets. When the ground faultoccurrence location is I, then if the respective levels of currentflowing in the inter-system switch 100 as shown in row (b) of FIG. 47,the first intra-system switch 201, and the first A individual switch301A exceed the threshold value of current Iα, the controller 500 judgesthat the level of current flow through the first B individual switch301B is equal to or less than the threshold value of current Iα. In thatcase, in step S51, of the first A individual switch 301A and the first Bindividual switch 301B, only the first A individual switch 301A isturned off.

When the ground fault occurrence location is G, then as shown in row (c)of FIG. 47, if the respective levels of current flow through theinter-system switch 100, the first intra-system switch 201, and thefirst B individual switch 301B exceed the threshold value of current Iα,the controller 500 judges that the level of current flowing through thefirst A individual switch 301A is equal to or less than the thresholdvalue of current Iα. In that case, of the first A individual switch 301Aand the first B individual switch 301B, only the first B individualswitch 301B is turned off in step S51.

When the ground fault occurrence location is C, then as shown in the row(a) of FIG. 47, if the respective levels of current flow through thethrough the inter-system switch 100 and the first intra-system switch201 exceed the threshold value of current Iα, the controller 500 judgesthat the respective levels of current flow through the first Aindividual switch 301A and the first B individual switch 301B are equalto or less than the threshold value of current Iα. In that case, thefirst A individual switch 301A and the first B individual switch 301Bare turned off in step S51. It should be noted that it is not essentialfor the first A individual switch 301A and the first B individual switch301B to be turned off, and these may be maintained in the turned-onstate.

If an affirmative decision is subsequently made in step S56, then of allthe switches that have been specified in step S51, only the individualswitches that were turned off in step S55 are maintained in theturned-on state.

With the present embodiment described above, a ground fault occurrencelocation can be reliably disconnected from the power supply system, evenwith a configuration in which each electrical load is connected to amain path via a dedicated individual switch.

Twenty-Fourth Embodiment

A twenty-fourth embodiment will be described in the following referringto the drawings, with a focus on points of difference from thetwenty-first to twenty-third embodiments. With the present embodiment,the configuration shown in FIG. 48 is used for a power supply system. InFIG. 48, configuration parts which are identical to parts shown in FIG.16 are designated by the same reference numerals as in FIG. 16, forconvenience.

With the present embodiment, the second inter-system switch 122 in FIG.16 is designated as a first inter-system switch 121A and the firstinter-system switch 121 in FIG. 16 is designated as a secondinter-system switch 121B. Furthermore, the path that connects thepositive electrode of the first power output section 11 to the part ofthe first path MLα which is enclosed between the first A intra-systemswitch 211A and the first B intra-system switch 211B is designated asthe first power supply path Mα. In addition, the path that connects thepositive electrode of the second power output section 12 to the part ofthe second path MLβ which is enclosed between the second A system switch212A and the second B system switch 212B is designated as the secondpower supply path Mβ.

The first power supply path Mα is provided with a first C intra-systemswitch 211C, and the second power supply path Mβ is provided with asecond C intra-system switch 212C. The first C intra-system switch 211Cand the second C intra-system switch 212C are operated by the controller500.

Furthermore, with the present embodiment also, a ground fault occurrencelocation can be disconnected from the power supply system by operationprocessing executed when an abnormality occurs, as described for thetwentieth to twenty-third embodiments. In FIG. 48, Z1 to Z3 showexamples of ground fault occurrence locations. Z1 is a part of the firstpower supply path Mα that is sandwiched between the first power supplyintra-system switch 211C and the positive electrode of the first poweroutput section 11. Z2 is a part of the first power supply path MLα thatis sandwiched between the first A intra-system switch 211A and the firstB intra-system switch 211B. Z3 is a part of the first power supply pathMLα that is sandwiched between the first inter-system switch 121A andthe first A intra-system switch 211A.

FIG. 49 shows the relationship between the ground fault occurrencelocations Z1 to Z3, the respective directions and magnitudes of currentflow through the switches 211C, 211A, 211B, 121A, 121B, 212A, 212B, and212C, and the inter-system switches and intra-system switches that arespecified as turn-off targets in step S51 of FIG. 41.

When the ground fault occurrence location is Z1, as shown in row (a) ofFIG. 49, it is judged that the directions of current flow in therespective switches 211C, 211A, 211B, 121A, 121B, 212A, 212B, 212C areeach identical. In that case, the first C intra-system switch 211C(corresponding to the target switch), which is the switch that is themost downstream among the switches 211C, 211A, 211B, 121A, 121B, 212A,212B, and 212C, with respect to the current flow direction, is specifiedas the turn-off target switch. Row (a) of FIG. 49 shows the case inwhich the levels of current flowing through each of the switches 211C,211A, 211B, 121A, 121B, 212A, 212B, and 212C exceed the threshold valueof current Iα.

When the ground fault occurrence location is Z2, then as shown in row(b) of FIG. 49, it is judged that the direction of current flow throughthe first C intra-system switch 211C is opposite the direction ofcurrent flow through each of the other switches 211A, 211B, 121A, 121B,212A, 212B, 212C. In addition, it is judged that the levels of currentflow exceed the threshold value of current Iα in each of the switches211C and 211A, 211B, which have been judged to have opposite directionsof current flow. In that case the first C intra-system switch 211C, andthe first A intra-system switch 211A and first B intra-system switch211B, which have opposite direction of current flow and for which thedetected levels of current flow exceed the threshold value of currentIα, are specified as turn-off operation targets (with the first C systemswitch 211C, first A system switch 211A and first B system switch 211Bcorresponding to a switch group).

When the ground fault occurrence location is Z3, as shown in row (c) ofFIG. 49, it is judged that the direction of current flow through thefirst C intra-system switch 211C and the first A intra-system switch211A is opposite the direction of current flow through the firstinter-system switch 121A, the second A intra-system switch 212A and thesecond C intra-system switch 212C. Furthermore, it is judged that thelevels of current in each of the switches 211A and 121A, for which ithas been judged that the respective directions of current flow areopposite one another, exceeds the threshold value of current Iα. In thatcase, the first intra-system switch 211A and the first intra-systemswitch 121A (corresponding to a switch group) in which the detecteddirections of current flow are opposite to one another and in which thelevel of current flow exceeds the threshold value of current Iα, arespecified as turn-off operation targets.

When the ground fault occurrence location is Z3, then as shown in row(d) in FIG. 49, unlike row (c) in FIG. 49, current may flow through thefirst B intra-system switch 211B, the second inter-system switch 121Band the second B intra-system switch 212B. Row (c) in FIG. 49 shows anexample in which the current flow directions through the secondinter-system switch 121B and the second B intra-system switch 212B areopposite one another. In that case, the second inter-system switch 121Band the second B intra-system switch 212B are specified as turn-offoperation targets. With the present embodiment, of a group of switcheswhose directions of current flow have been judged to be opposite oneanother, only the switches for which it is judged that the direction ofcurrent flow exceeds the threshold value of current Iα are targeted forturn-off operation. As a result, it is possible to prevent switches frombeing erroneously specified as turn-off operation targets.

It should be noted that with the present embodiment, the abnormalityoccurrence operation processing described for the twenty-first andtwenty-third embodiments may be applied when there is an individualswitch connected to a part of a main path which is sandwiched between aninter-system switch and an intra-system switch.

With the present embodiment described above, it is possible toaccurately specify a switch as a turn-off operation target, in aconfiguration whereby the main paths are formed in a ring.

Twenty-Fifth Embodiment

A twenty-fifth embodiment will be described in the following referringto the drawings, with a focus on points of difference from thetwenty-first embodiment. With the present embodiment, a power supplysystem has the configuration shown in FIG. 50. In FIG. 50, componentsthat are identical to components shown in FIG. 35 are designated by thesame reference numerals as in FIG. 35, for convenience.

The power supply system includes a first module MA and a second moduleMB. The first module MA includes a first intra-system switch 201, afirst inter-system switch 171 and a first controller 500A. The secondmodule MB includes a second intra-system switch 202, a secondinter-system switch 172, and a second controller 500B. The first moduleMA corresponds to the first system ES1, and the second module MBcorresponds to the second system ES2.

The first intra-system switch 201 includes a first A intra-system switch201 a and a first B intra-system switch 201 b. The first A intra-systemswitch 201 a and the first B intra-system switch 201 b are N-channel MOSFETs. The first power output section 11 is connected to the drain of thefirst A intra-system switch 201 a via the first path ML1. The source ofthe first B intra-system switch 201 b is connected to the source of thefirst A intra-system switch 201 a.

The first inter-system switch 171 includes a first A inter-system switch171 a and a first B inter-system switch 171 b. The first A inter-systemswitch 171 a and the first B inter-system switch 171 b are N-channel MOSFETs. The drain of the first A intra-system switch 171 a is connected tothe drain of the first B intra-system switch 201 b via the first pathML1.

The second intra-system switch 202 includes a second A intra-systemswitch 202 a and a second B intra-system switch 202 b. The second Aintra-system switch 202 a and the second B intra-system switch 202 b areN-channel MOS FETs. The second power output section 12 is connected tothe drain of the second B intra-system switch 202 b via the second pathML2.

The second inter-system switch 172 includes a second A inter-systemswitch 172 a and a second B inter-system switch 172 b. The second Ainter-system switch 172 a and the second B inter-system switch 172 b areN-channel MOS FETs. The drain of the second B inter-system switch 172 bis connected to the source of the second A intra-system switch 202 a viathe second path ML2. The drain of the second A inter-system switch 172 ais connected to the drain of the first B inter-system switch 171 b via acentral path MLM, which is provided as a main path of the power supplysystem.

The first module MA includes first to fourth drivers 511 to 514 andfirst to fourth current detectors 521 to 524. The first driver 511operates the first A intra-system switch 201 a in response to commandsreceived from the first controller 500A. The second driver 512 operatesthe first B intra-system switch 201 b in response to commands receivedfrom the first controller 500A. The third driver 513 operates the firstA inter-system switch 171 a in response to commands received from thefirst controller 500A. The fourth driver 514 operates the first Bintra-system switch 171 b in response to commands received from thefirst controller 500A.

The first current detector 521 detects the current flowing through thefirst A intra-system switch 201 a. The second current detector 522detects the current flowing through the first B intra-system switch 201b. The third current detector 523 detects the current flowing throughthe first A inter-system switch 171 a. The fourth current detector 524detects the current flowing through the first B inter-system switch 171b. Each of the current detectors 521 to 524 may, for example, detect thecurrent flow information for the switch that is its detection object bydetecting the inter-terminal voltage Vds of the switch, as described forthe twentieth embodiment.

The detection values of the first to fourth current detectors 521 to 524are inputted to the first controller 500A. The first controller 500Adetects the magnitude of each of the currents flowing through theswitches 201 a, 201 b, 171 a, 171 b, and the flow direction of eachcurrent, based on the detection values from the current detectors 521 to524.

The second module MB includes fifth to eighth drivers 515 to 518 andfifth to eighth current detectors 525 to 528. The fifth driver 515operates the second inter-system switch 172 a in response to commandsreceived from the second controller 500B. The sixth driver 516 operatesthe second B inter-system switch 172 b in response to commands receivedfrom the second controller 500B. The seventh driver 517 operates thesecond A intra-system switch 202 a in response to commands received fromthe second controller 500B. The eighth driver 518 operates the second Bintra-system switch 202 b in response to commands received from thesecond controller 500B.

The fifth current detector 525 detects the current flowing through thesecond A inter-system switch 172 a. The sixth current detector 526detects the current flowing through the second B inter-system switch 172b. The seventh current detector 527 detects the current flowing throughthe second A intra-system switch 202 a. The eighth current detector 528detects the current flowing through the second B intra-system switch 202b. Each of the current detectors 525 to 528 may, for example, detect thecurrent flow information for the switch that is its detection object bydetecting the inter-terminal voltage Vds of the switch, as described forthe twentieth embodiment,

The detection values from the fifth to eighth current detectors 525 to528 are inputted to the second controller 500B. The second controller500B detects the magnitude of each of the currents flowing through theswitches 202 a, 202 b, 172 a, 172 b, and the direction of flow of thecurrent, based on the detection values from the current detectors 525 to528.

The first controller 500A and the second controller 500B can exchangeinformation with one another. With the present embodiment, theabnormality occurrence operation processing that has been described forthe twentieth embodiment can be performed by cooperation between thefirst controller 500A and the second controller 500B. For example, ifthe ground fault occurrence location is G, shown in FIG. 38 above, thefirst intra-system switch 201 and the first inter-system switch 171 arespecified in step S51 of FIG. 37. This specifying can be performed bythe first controller 500A alone. On the other hand, for example when theground fault occurrence location is the central path MLM, the firstinter-system switch 171 and the second inter-system switch 172 arespecified in step S51 of FIG. 37. This specifying can be performed bycooperation between the first controller 500A and the second controller500B.

With the present embodiment, a power supply system is provided thatincludes first and second modules MA and MB, in each of which aplurality of switches, current detectors, and a controller aremodularized. As a result, processing for specifying ground faultlocations, and operation of the switches built into each module, can becompleted within the module concerned as far as possible. As a result,when a ground fault occurs, delays in processing executed by thecontrollers 500A and 500B, such as processing for operating switchesthat have become targets of turn-off operation, can be suppressed. Henceit is possible to suppress a delay between the occurrence of a groundfault and the disconnection of the ground fault occurrence location fromthe power supply system.

Modification Examples of Twenty-Fifth Embodiment

Instead of a configuration in which the first controller 500A and thesecond controller 500B are capable of exchanging information with oneanother, the power supply system may include a controller that is at ahigher level than the first controller 500A and the second controller500B. In that case, the high-level controller becomes the main body forexecuting operation processing when an abnormality occurs.

The configuration described for the twenty-fifth embodiment is equallyapplicable to the twenty-first to twenty-fourth embodiments.

The number of switches constituting the inter-system switch and theintra-system switch is not limited to two, and may be from four tosixteen switches as shown in FIGS. 32 to 34 for example. The presentinvention is not limited to a configuration in which current detectorsare provided individually for each of the switching devices thatconstitute an inter-system switch or an intra-system switch. As shown inFIG. 51, a configuration may be used in which current detectors areprovided for each of respective inter-system switches and intra-systemswitches. In FIG. 51, components corresponding to components shown inFIG. 50 are designated by the same reference numerals as in FIG. 50, forconvenience.

The power supply system includes first to fourth current detectors 531to 534. The first current detector 531 detects the current flowingthrough the first intra-system switch 201, and the second currentdetector 532 detects the current flowing through the first inter-systemswitch 171. The third current detector 533 detects the current flowingthrough the second inter-system switch 172, and the fourth currentdetector 534 detects the current flowing through the second intra-systemswitch 202. The detection values from the first and second currentdetectors 531 and 532 are inputted to the first controller 500A. Thedetection values from the third and fourth current detectors 533 and 534are inputted to the second controller 500B.

OTHER EMBODIMENTS

It should be noted that each of the above embodiments may be modified asfollows.

The configuration on the first system ES1 side in FIG. 1 may be changedto the configuration shown in FIG. 52.

In the first to nineteenth embodiments, the fuses of the thirdembodiment may be used in place of the individual switches.

The travel control is not limited to lane keeping support control, butmay be the following types of control, for example.

Anti-lock braking control, which prevents the wheels from locking duringbraking control, may be used. In that case, the first and secondredundant loads may be respective ABS actuators which can independentlyadjust the brake hydraulic pressure of each wheel during braking.

The control may be cruise control, whereby when a preceding vehicle isdetected that is traveling at a lower speed than a set speed, the hostvehicle is decelerated by braking control to maintain a specificinter-vehicle distance, and when the preceding vehicle is no longerdetected, the host vehicle is accelerated to travel at the set speed.With that configuration, the preceding vehicle may be detected by thefirst B and second B redundant loads 31B and 32B in FIG. 9. In thatcase, at least one of the first B and second B redundant loads 31B and32B may be a millimeter wave radar apparatus. Furthermore, in that case,the first A and second A redundant loads 31A and 32A in FIG. 9 may berespective ABS actuators.

The control may be an automatic braking control, which automaticallyapplies a braking force to the wheels when a vehicle or a pedestrian infront of the host vehicle is detected by the first B and second Bredundant loads 31B and 32B shown in FIG. 11. In that case, at least oneof the first B and second B redundant loads 31B and 32B may be amillimeter wave radar apparatus. Furthermore, in that case, the first Aand second A redundant loads 31A and 32A in FIG. 9 may be respective ABSactuators.

The control may be lane change support control, which monitors a blindspot at the rear of the host vehicle, by means of the first B and secondB redundant loads 31B and 32B shown in FIG. 11, and which warns thedriver of danger when making a lane change. Furthermore, the control maybe lane departure warning control which warns the driver when the hostvehicle is likely to depart from the travel lane, based on detectioninformation from the first B and second B redundant loads 31B and 32B.

Among the power supply systems shown in the above embodiments, forexample in the case of a power supply system in which the main paths arenot connected in a ring configuration, power output sections areconnected to respective ends of a main path via an inter-system switch,however the configuration is not limited to this. For example, a poweroutput section may be connected to a position, in one of respective mainpaths that are connected via inter-system switches, that is sandwichedbetween a connection point of one electrical load to the main path and aconnection point of another electrical load to the main path. FIG. 53shows an example of this configuration. In the configuration shown inFIG. 53, the first power output section 11 is connected at a positionbetween the connection point of first A and B normal loads 21A and 21Bto the first path MLα and the connection point of the first redundantload 31 to the first path MLα. Moreover, the second power output section12 is connected to a position in the second path MLβ that is between therespective connection points of the second normal load 22 and the secondredundant load 32 to the second path MLβ. In FIG. 53, components thatare identical to components shown in FIG. 16 above are designated by thesame reference numerals as in FIG. 16, for convenience.

With the first to nineteenth embodiments, turn-on operations areexecuted sequentially on the target system, starting from the one of theintra-system switches and individual switches that is closest to a poweroutput section, however the present invention is not limited to this.For example, in the target system, turn-on operations may be executedsequentially starting from the one of the intra-system switches that isclosest to a power output section, and thereafter executed sequentiallystarting from the one of the individual switches that is closest to thepower output section.

The storage device may for example be a fuel cell, that generateselectric power based on hydrogen supplied from a hydrogen storage tank,or may be a capacitor such as an electrical two-layer capacitor or alithium-ion capacitor, etc.

The DC-DC converter may have only the step-down function, or have onlythe step-up function.

The vehicle in which the power supply system is installed is not limitedto a vehicle having only an engine as a main machine, but may be avehicle having only a rotary electrical machine, for example.Furthermore, the power supply system is not limited to being destinedfor installation on vehicle.

Although the present disclosure has been described based on embodiments,it is understood that the disclosure is not limited to these embodimentsand the structures thereof. The present disclosure encompasses variousmodified forms and changes that come within an equivalent scope.Furthermore, various combinations and forms, including othercombinations and forms that contain one or more elements, also comewithin the scope and range of concepts of the present disclosure.

What is claimed is:
 1. A power supply system having a plurality of powersystems, comprising: a power output section in each of the plurality ofpower systems, that is configured to output electric power; anelectrical load in the each of the plurality of power systems, that isconfigured to operate from electric power supplied by one of the poweroutput sections; main paths that connect the power output sections ofeach adjacent pair of the plurality of power systems; an inter-systemswitch in each of the main paths, which is configured to be (1) turnedon to establish a conducting state between the each adjacent pair of theplurality of power systems and (2) turned off to establish adisconnected state between the each adjacent pair of the plurality ofpower systems; an intra-system switch in the each of the plurality ofpower systems, in a part of the each of the main paths that is closer tothe power output section than is the inter-system switch, and which isconfigured to be (1) turned on to establish a conducting state betweenthe power output section and the electrical load and (2) turned off toestablish a disconnected state between the power output section and theelectrical load; a current detector in the each of the plurality ofpower systems, that is configured to detect an output current from oneof the power output sections; a current judgement section configured tojudge when the output current detected by the current detector is abovea threshold value of current; an inter-system operating section that isconfigured to turn off the inter-system switch, for establishing adisconnected state between the each adjacent pair of the plurality ofpower systems, in response to the current judgement section judging thatthe output current detected by the current detector in at least one ofthe each adjacent pair of the plurality of power systems exceeds thethreshold value of current; an individual switch in the each of theplurality of power systems, that is configured to establish a conductingstate between the electrical load and one of the each of the main pathswhen turned on and a disconnected state between the electrical load andthe one of the each of the main paths when turned off; and anintra-system operating section that is configured to, when it is judgedthat the output current detected by the current detector that exceeds athreshold value of current, specify the power system as a target system,and which, designate the threshold value of current as a first thresholdvalue of current, turn off the individual switch and the intra-systemswitch of the target system if, after the inter-system switch has beenturned off by the inter-system operating section, it is judged that theoutput current detected by the current detector exceeds a secondthreshold value of current that is higher than the first threshold valueof current.
 2. The power supply system according to claim 1, wherein aplurality of electrical loads are in the each of the plurality of powersystems, each of the plurality of electrical loads includes anindividual switch, the intra-system operating section is configured toexecute turn-on and turn-off operations on each of the individualswitches and each of the intra-system switches in the target system,wherein the power supply system further includes: a first changeoveroperating section that is configured to sequentially turn on each of theindividual switches in the target system, after the each of theindividual switches have been turned off by the intra-system operatingsection; a specifying section that is configured to specify any of theindividual switches in the target system which have been turned on bythe first changeover operating section and for which the output currentdetected by the current detector exceeds the second threshold value ofcurrent; and a second changeover operating section that is configured toturn off those of the individual switches in the target system whichhave been specified by the specifying section, and turn on each of otherindividual switches.
 3. The power supply system according to claim 1,wherein the power supply system is has three or more of the powersystems; and the intra-system operating section is configured to, whenthe power system is specified as the target system, if it is judged thata conducting condition can be established between at least two of theplurality of power systems other than the target system after theinter-system switch has been turned off to establish a disconnectedcondition between the at least two of the plurality of power systems,turn on the inter-system switch, to establish the conducting conditionbetween the at least two of the plurality of power systems.
 4. The powersupply system according to claim 1, further comprising: a voltagedetector in the each of the plurality power systems, that is configuredto detect the output voltage from the power output section; a voltagejudgement section, that is configured to judge when the output voltagethat is detected by the voltage detector is below a threshold value ofvoltage; and the inter-system operating section is configured to turnoff the inter-system switch to establish a disconnected conditionbetween the power systems of the plurality of power systems in responseto, in at least one of the plurality of power systems, the voltagejudgement section thereof judging that the output voltage detected bythe voltage detector has fallen below the threshold value of voltage. 5.The power supply system according to claim 4, wherein the intra-systemoperating section is configured to specify the power system as thetarget system when the output voltage of the power system, detected bythe voltage detector, is below the threshold value of voltage and which,designate the threshold value of voltage as the first threshold value ofvoltage, turn off the individual switch and the intra-system switch inthe target system in response to, after the inter-system switch has beenturned off by the inter-system operating section, the output voltage ofthe target system, detected by the voltage detector, falling below asecond threshold value of voltage that is lower than the first thresholdvalue of voltage.
 6. The power supply system according to claim 5,wherein a plurality of the electrical loads are in the each of theplurality of power systems, each of the plurality of electrical loadsincludes an individual switch, in the intra-system operating section isconfigured to turn off each of the individual switches and theintra-system switches in the target system; the power supply systemfurther includes: a first changeover operating section that isconfigured to sequentially turn on each of the individual switches inthe target system after the individual switches have been turned off bythe intra-system operating section; a specifying section that isconfigured to, when the each of the individual switches of the targetsystem is turned on by the first changeover operating section, specifyany of the individual switches for which the output voltage, detected bythe voltage detector, is below the second threshold value of voltage;and a second changeover operating section, that is configured to turnoff any individual switch that is among the individual switches of thetarget system and has been specified by the specifying section, and turnon other individual switches.
 7. The power supply system according toclaim 4, wherein the power supply system has three or more of the powersystems; and the inter-system operating section is configured to, whenthe power system is specified as the target system, if it is judged thata conducting condition can be established via the inter-system switchbetween at least two of the plurality of power systems other than thetarget system after the inter-system switch has been turned off toestablish a disconnected condition between the at least two of theplurality of power systems, turn on the inter-system switch, toestablish the conducting condition between the at least two of theplurality of power systems.
 8. The power supply system according toclaim 1, further comprising a fuse between the electrical load and themain path in the each of the plurality of power systems.
 9. The powersupply system according to claim 8, wherein the intra-system operatingsection is configured to, in response to the output current detected bythe current detector being judged to exceed the threshold value ofcurrent and the power system is specified as the target system, turn offthe intra-system switch of the target system if it is judged that theoutput current from the target system has continued to increase after apredetermined time elapsed since the inter-system switch was turned offby the inter-system operating section.